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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Y. Nir 3 Internet-Draft Check Point 4 Intended status: Informational A. Langley 5 Expires: January 24, 2015 Google Inc 6 July 23, 2014 8 ChaCha20 and Poly1305 for IETF protocols 9 draft-irtf-cfrg-chacha20-poly1305-00 11 Abstract 13 This document defines the ChaCha20 stream cipher, as well as the use 14 of the Poly1305 authenticator, both as stand-alone algorithms, and as 15 a "combined mode", or Authenticated Encryption with Additional Data 16 (AEAD) algorithm. 18 This document does not introduce any new crypto, but is meant to 19 serve as a stable reference and an implementation guide. 21 Status of this Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on January 24, 2015. 38 Copyright Notice 40 Copyright (c) 2014 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 1.1. Conventions Used in This Document . . . . . . . . . . . . 3 54 2. The Algorithms . . . . . . . . . . . . . . . . . . . . . . . . 4 55 2.1. The ChaCha Quarter Round . . . . . . . . . . . . . . . . . 4 56 2.1.1. Test Vector for the ChaCha Quarter Round . . . . . . . 4 57 2.2. A Quarter Round on the ChaCha State . . . . . . . . . . . 5 58 2.2.1. Test Vector for the Quarter Round on the ChaCha 59 state . . . . . . . . . . . . . . . . . . . . . . . . 5 60 2.3. The ChaCha20 block Function . . . . . . . . . . . . . . . 6 61 2.3.1. Test Vector for the ChaCha20 Block Function . . . . . 7 62 2.4. The ChaCha20 encryption algorithm . . . . . . . . . . . . 8 63 2.4.1. Example and Test Vector for the ChaCha20 Cipher . . . 9 64 2.5. The Poly1305 algorithm . . . . . . . . . . . . . . . . . . 11 65 2.5.1. Poly1305 Example and Test Vector . . . . . . . . . . . 13 66 2.6. Generating the Poly1305 key using ChaCha20 . . . . . . . . 14 67 2.6.1. Poly1305 Key Generation Test Vector . . . . . . . . . 15 68 2.7. A Pseudo-Random Function for ChaCha/Poly-1305 based 69 Crypto Suites . . . . . . . . . . . . . . . . . . . . . . 16 70 2.8. AEAD Construction . . . . . . . . . . . . . . . . . . . . 16 71 2.8.1. Example and Test Vector for AEAD_CHACHA20-POLY1305 . . 18 72 3. Implementation Advice . . . . . . . . . . . . . . . . . . . . 20 73 4. Security Considerations . . . . . . . . . . . . . . . . . . . 20 74 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 75 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21 76 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 77 7.1. Normative References . . . . . . . . . . . . . . . . . . . 22 78 7.2. Informative References . . . . . . . . . . . . . . . . . . 22 79 Appendix A. Additional Test Vectors . . . . . . . . . . . . . . . 23 80 A.1. The ChaCha20 Block Functions . . . . . . . . . . . . . . . 23 81 A.2. ChaCha20 Encryption . . . . . . . . . . . . . . . . . . . 26 82 A.3. Poly1305 Message Authentication Code . . . . . . . . . . . 28 83 A.4. Poly1305 Key Generation Using ChaCha20 . . . . . . . . . . 34 84 A.5. ChaCha20-Poly1305 AEAD Decryption . . . . . . . . . . . . 35 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 87 1. Introduction 89 The Advanced Encryption Standard (AES - [FIPS-197]) has become the 90 gold standard in encryption. Its efficient design, wide 91 implementation, and hardware support allow for high performance in 92 many areas. On most modern platforms, AES is anywhere from 4x to 10x 93 as fast as the previous most-used cipher, 3-key Data Encryption 94 Standard (3DES - [FIPS-46]), which makes it not only the best choice, 95 but the only practical choice. 97 The problem is that if future advances in cryptanalysis reveal a 98 weakness in AES, users will be in an unenviable position. With the 99 only other widely supported cipher being the much slower 3DES, it is 100 not feasible to re-configure implementations to use 3DES. 101 [standby-cipher] describes this issue and the need for a standby 102 cipher in greater detail. 104 This document defines such a standby cipher. We use ChaCha20 105 ([chacha]) with or without the Poly1305 ([poly1305]) authenticator. 106 These algorithms are not just fast. They are fast even in software- 107 only C-language implementations, allowing for much quicker deployment 108 when compared with algorithms such as AES that are significantly 109 accelerated by hardware implementations. 111 This document does not introduce these new algorithms. They have 112 been defined in scientific papers by D. J. Bernstein, which are 113 referenced by this document. The purpose of this document is to 114 serve as a stable reference for IETF documents making use of these 115 algorithms. 117 These algorithms have undergone rigorous analysis. Several papers 118 discuss the security of Salsa and ChaCha ([LatinDances], 119 [Zhenqing2012]). 121 1.1. Conventions Used in This Document 123 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 124 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 125 document are to be interpreted as described in [RFC2119]. 127 The description of the ChaCha algorithm will at various time refer to 128 the ChaCha state as a "vector" or as a "matrix". This follows the 129 use of these terms in DJB's paper. The matrix notation is more 130 visually convenient, and gives a better notion as to why some rounds 131 are called "column rounds" while others are called "diagonal rounds". 132 Here's a diagram of how to matrices relate to vectors (using the C 133 language convention of zero being the index origin). 135 0 1 2 3 136 4 5 6 7 137 8 9 10 11 138 12 13 14 15 140 The elements in this vector or matrix are 32-bit unsigned integers. 142 The algorithm name is "ChaCha". "ChaCha20" is a specific instance 143 where 20 "rounds" (or 80 quarter rounds - see Section 2.1) are used. 144 Other variations are defined, with 8 or 12 rounds, but in this 145 document we only describe the 20-round ChaCha, so the names "ChaCha" 146 and "ChaCha20" will be used interchangeably. 148 2. The Algorithms 150 The subsections below describe the algorithms used and the AEAD 151 construction. 153 2.1. The ChaCha Quarter Round 155 The basic operation of the ChaCha algorithm is the quarter round. It 156 operates on four 32-bit unsigned integers, denoted a, b, c, and d. 157 The operation is as follows (in C-like notation): 158 o a += b; d ^= a; d <<<= 16; 159 o c += d; b ^= c; b <<<= 12; 160 o a += b; d ^= a; d <<<= 8; 161 o c += d; b ^= c; b <<<= 7; 162 Where "+" denotes integer addition modulo 2^32, "^" denotes a bitwise 163 XOR, and "<<< n" denotes an n-bit left rotation (towards the high 164 bits). 166 For example, let's see the add, XOR and roll operations from the 167 first line with sample numbers: 168 o b = 0x01020304 169 o a = 0x11111111 170 o d = 0x01234567 171 o a = a + b = 0x11111111 + 0x01020304 = 0x12131415 172 o d = d ^ a = 0x01234567 ^ 0x12131415 = 0x13305172 173 o d = d<<<16 = 0x51721330 175 2.1.1. Test Vector for the ChaCha Quarter Round 177 For a test vector, we will use the same numbers as in the example, 178 adding something random for c. 179 o a = 0x11111111 180 o b = 0x01020304 181 o c = 0x9b8d6f43 182 o d = 0x01234567 184 After running a Quarter Round on these 4 numbers, we get these: 185 o a = 0xea2a92f4 186 o b = 0xcb1cf8ce 187 o c = 0x4581472e 188 o d = 0x5881c4bb 190 2.2. A Quarter Round on the ChaCha State 192 The ChaCha state does not have 4 integer numbers, but 16. So the 193 quarter round operation works on only 4 of them - hence the name. 194 Each quarter round operates on 4 pre-determined numbers in the ChaCha 195 state. We will denote by QUATERROUND(x,y,z,w) a quarter-round 196 operation on the numbers at indexes x, y, z, and w of the ChaCha 197 state when viewed as a vector. For example, if we apply 198 QUARTERROUND(1,5,9,13) to a state, this means running the quarter 199 round operation on the elements marked with an asterisk, while 200 leaving the others alone: 202 0 *a 2 3 203 4 *b 6 7 204 8 *c 10 11 205 12 *d 14 15 207 Note that this run of quarter round is part of what is called a 208 "column round". 210 2.2.1. Test Vector for the Quarter Round on the ChaCha state 212 For a test vector, we will use a ChaCha state that was generated 213 randomly: 215 Sample ChaCha State 217 879531e0 c5ecf37d 516461b1 c9a62f8a 218 44c20ef3 3390af7f d9fc690b 2a5f714c 219 53372767 b00a5631 974c541a 359e9963 220 5c971061 3d631689 2098d9d6 91dbd320 222 We will apply the QUARTERROUND(2,7,8,13) operation to this state. 223 For obvious reasons, this one is part of what is called a "diagonal 224 round": 226 After applying QUARTERROUND(2,7,8,13) 228 879531e0 c5ecf37d bdb886dc c9a62f8a 229 44c20ef3 3390af7f d9fc690b cfacafd2 230 e46bea80 b00a5631 974c541a 359e9963 231 5c971061 ccc07c79 2098d9d6 91dbd320 233 Note that only the numbers in positions 2, 7, 8, and 13 changed. 235 2.3. The ChaCha20 block Function 237 The ChaCha block function transforms a ChaCha state by running 238 multiple quarter rounds. 240 The inputs to ChaCha20 are: 241 o A 256-bit key, treated as a concatenation of 8 32-bit little- 242 endian integers. 243 o A 96-bit nonce, treated as a concatenation of 3 32-bit little- 244 endian integers. 245 o A 32-bit block count parameter, treated as a 32-bit little-endian 246 integer. 248 The output is 64 random-looking bytes. 250 The ChaCha algorithm described here uses a 256-bit key. The original 251 algorithm also specified 128-bit keys and 8- and 12-round variants, 252 but these are out of scope for this document. In this section we 253 describe the ChaCha block function. 255 Note also that the original ChaCha had a 64-bit nonce and 64-bit 256 block count. We have modified this here to be more consistent with 257 recommendations in section 3.2 of [RFC5116]. This limits the use of 258 a single (key,nonce) combination to 2^32 blocks, or 256 GB, but that 259 is enough for most uses. In cases where a single key is used by 260 multiple senders, it is important to make sure that they don't use 261 the same nonces. This can be assured by partitioning the nonce space 262 so that the first 32 bits are unique per sender, while the other 64 263 bits come from a counter. 265 The ChaCha20 state is initialized as follows: 266 o The first 4 words (0-3) are constants: 0x61707865, 0x3320646e, 267 0x79622d32, 0x6b206574. 268 o The next 8 words (4-11) are taken from the 256-bit key by reading 269 the bytes in little-endian order, in 4-byte chunks. 270 o Word 12 is a block counter. Since each block is 64-byte, a 32-bit 271 word is enough for 256 Gigabytes of data. 273 o Words 13-15 are a nonce, which should not be repeated for the same 274 key. The 13th word is the first 32 bits of the input nonce taken 275 as a little-endian integer, while the 15th word is the last 32 276 bits. 278 cccccccc cccccccc cccccccc cccccccc 279 kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk 280 kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk 281 bbbbbbbb nnnnnnnn nnnnnnnn nnnnnnnn 283 c=constant k=key b=blockcount n=nonce 285 ChaCha20 runs 20 rounds, alternating between "column" and "diagonal" 286 rounds. Each round is 4 quarter-rounds, and they are run as follows. 287 Quarter-rounds 1-4 are part of a "column" round, while 5-8 are part 288 of a "diagonal" round: 289 1. QUARTERROUND ( 0, 4, 8,12) 290 2. QUARTERROUND ( 1, 5, 9,13) 291 3. QUARTERROUND ( 2, 6,10,14) 292 4. QUARTERROUND ( 3, 7,11,15) 293 5. QUARTERROUND ( 0, 5,10,15) 294 6. QUARTERROUND ( 1, 6,11,12) 295 7. QUARTERROUND ( 2, 7, 8,13) 296 8. QUARTERROUND ( 3, 4, 9,14) 298 At the end of 20 rounds, we add the original input words to the 299 output words, and serialize the result by sequencing the words one- 300 by-one in little-endian order. 302 Note: "addition" in the above paragraph is done modulo 2^32. In some 303 machine languages this is called carryless addition on a 32-bit word. 305 2.3.1. Test Vector for the ChaCha20 Block Function 307 For a test vector, we will use the following inputs to the ChaCha20 308 block function: 309 o Key = 00:01:02:03:04:05:06:07:08:09:0a:0b:0c:0d:0e:0f:10:11:12:13: 310 14:15:16:17:18:19:1a:1b:1c:1d:1e:1f. The key is a sequence of 311 octets with no particular structure before we copy it into the 312 ChaCha state. 313 o Nonce = (00:00:00:09:00:00:00:4a:00:00:00:00) 314 o Block Count = 1. 316 After setting up the ChaCha state, it looks like this: 318 ChaCha State with the key set up. 320 61707865 3320646e 79622d32 6b206574 321 03020100 07060504 0b0a0908 0f0e0d0c 322 13121110 17161514 1b1a1918 1f1e1d1c 323 00000001 09000000 4a000000 00000000 325 After running 20 rounds (10 column rounds interleaved with 10 326 diagonal rounds), the ChaCha state looks like this: 328 ChaCha State after 20 rounds 330 837778ab e238d763 a67ae21e 5950bb2f 331 c4f2d0c7 fc62bb2f 8fa018fc 3f5ec7b7 332 335271c2 f29489f3 eabda8fc 82e46ebd 333 d19c12b4 b04e16de 9e83d0cb 4e3c50a2 335 Finally we add the original state to the result (simple vector or 336 matrix addition), giving this: 338 ChaCha State at the end of the ChaCha20 operation 340 e4e7f110 15593bd1 1fdd0f50 c47120a3 341 c7f4d1c7 0368c033 9aaa2204 4e6cd4c3 342 466482d2 09aa9f07 05d7c214 a2028bd9 343 d19c12b5 b94e16de e883d0cb 4e3c50a2 345 After we serialize the state, we get this: 347 Serialized Block: 348 000 10 f1 e7 e4 d1 3b 59 15 50 0f dd 1f a3 20 71 c4 .....;Y.P.... q. 349 016 c7 d1 f4 c7 33 c0 68 03 04 22 aa 9a c3 d4 6c 4e ....3.h.."....lN 350 032 d2 82 64 46 07 9f aa 09 14 c2 d7 05 d9 8b 02 a2 ..dF............ 351 048 b5 12 9c d1 de 16 4e b9 cb d0 83 e8 a2 50 3c 4e ......N......P.S. 813 Poly1305 r = 455e9a4057ab6080f47b42c052bac7b 814 Poly1305 s = ff53d53e7875932aebd9751073d6e10a 816 Keystream bytes: 817 9f:7b:e9:5d:01:fd:40:ba:15:e2:8f:fb:36:81:0a:ae: 818 c1:c0:88:3f:09:01:6e:de:dd:8a:d0:87:55:82:03:a5: 819 4e:9e:cb:38:ac:8e:5e:2b:b8:da:b2:0f:fa:db:52:e8: 820 75:04:b2:6e:be:69:6d:4f:60:a4:85:cf:11:b8:1b:59: 821 fc:b1:c4:5f:42:19:ee:ac:ec:6a:de:c3:4e:66:69:78: 822 8e:db:41:c4:9c:a3:01:e1:27:e0:ac:ab:3b:44:b9:cf: 823 5c:86:bb:95:e0:6b:0d:f2:90:1a:b6:45:e4:ab:e6:22: 824 15:38 826 Ciphertext: 827 000 d3 1a 8d 34 64 8e 60 db 7b 86 af bc 53 ef 7e c2 ...4d.`.{...S.~. 828 016 a4 ad ed 51 29 6e 08 fe a9 e2 b5 a7 36 ee 62 d6 ...Q)n......6.b. 829 032 3d be a4 5e 8c a9 67 12 82 fa fb 69 da 92 72 8b =..^..g....i..r. 830 048 1a 71 de 0a 9e 06 0b 29 05 d6 a5 b6 7e cd 3b 36 .q.....)....~.;6 831 064 92 dd bd 7f 2d 77 8b 8c 98 03 ae e3 28 09 1b 58 ....-w......(..X 832 080 fa b3 24 e4 fa d6 75 94 55 85 80 8b 48 31 d7 bc ..$...u.U...H1.. 833 096 3f f4 de f0 8e 4b 7a 9d e5 76 d2 65 86 ce c6 4b ?....Kz..v.e...K 834 112 61 16 a. 836 AEAD Construction for Poly1305: 837 000 50 51 52 53 c0 c1 c2 c3 c4 c5 c6 c7 00 00 00 00 PQRS............ 838 016 d3 1a 8d 34 64 8e 60 db 7b 86 af bc 53 ef 7e c2 ...4d.`.{...S.~. 839 032 a4 ad ed 51 29 6e 08 fe a9 e2 b5 a7 36 ee 62 d6 ...Q)n......6.b. 840 048 3d be a4 5e 8c a9 67 12 82 fa fb 69 da 92 72 8b =..^..g....i..r. 841 064 1a 71 de 0a 9e 06 0b 29 05 d6 a5 b6 7e cd 3b 36 .q.....)....~.;6 842 080 92 dd bd 7f 2d 77 8b 8c 98 03 ae e3 28 09 1b 58 ....-w......(..X 843 096 fa b3 24 e4 fa d6 75 94 55 85 80 8b 48 31 d7 bc ..$...u.U...H1.. 844 112 3f f4 de f0 8e 4b 7a 9d e5 76 d2 65 86 ce c6 4b ?....Kz..v.e...K 845 128 61 16 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a............... 846 144 0c 00 00 00 00 00 00 00 72 00 00 00 00 00 00 00 ........r....... 848 Note the 4 zero bytes in line 000 and the 14 zero bytes in line 128 850 Tag: 851 1a:e1:0b:59:4f:09:e2:6a:7e:90:2e:cb:d0:60:06:91 853 3. Implementation Advice 855 Each block of ChaCha20 involves 16 move operations and one increment 856 operation for loading the state, 80 each of XOR, addition and Roll 857 operations for the rounds, 16 more add operations and 16 XOR 858 operations for protecting the plaintext. Section 2.3 describes the 859 ChaCha block function as "adding the original input words". This 860 implies that before starting the rounds on the ChaCha state, we copy 861 it aside, only to add it in later. This is correct, but we can save 862 a few operations if we instead copy the state and do the work on the 863 copy. This way, for the next block you don't need to recreate the 864 state, but only to increment the block counter. This saves 865 approximately 5.5% of the cycles. 867 It is not recommended to use a generic big number library such as the 868 one in OpenSSL for the arithmetic operations in Poly1305. Such 869 libraries use dynamic allocation to be able to handle any-sized 870 integer, but that flexibility comes at the expense of performance as 871 well as side-channel security. More efficient implementations that 872 run in constant time are available, one of them in DJB's own library, 873 NaCl ([NaCl]). A constant-time but not optimal approach would be to 874 naively implement the arithmetic operations for a 288-bit integers, 875 because even a naive implementation will not exceed 2^288 in the 876 multiplication of (acc+block) and r. An efficient constant-time 877 implementation can be found in the public domain library poly1305- 878 donna ([poly1305_donna]). 880 4. Security Considerations 882 The ChaCha20 cipher is designed to provide 256-bit security. 884 The Poly1305 authenticator is designed to ensure that forged messages 885 are rejected with a probability of 1-(n/(2^102)) for a 16n-byte 886 message, even after sending 2^64 legitimate messages, so it is SUF- 887 CMA in the terminology of [AE]. 889 Proving the security of either of these is beyond the scope of this 890 document. Such proofs are available in the referenced academic 891 papers. 893 The most important security consideration in implementing this draft 894 is the uniqueness of the nonce used in ChaCha20. Counters and LFSRs 895 are both acceptable ways of generating unique nonces, as is 896 encrypting a counter using a 64-bit cipher such as DES. Note that it 897 is not acceptable to use a truncation of a counter encrypted with a 898 128-bit or 256-bit cipher, because such a truncation may repeat after 899 a short time. 901 The Poly1305 key MUST be unpredictable to an attacker. Randomly 902 generating the key would fulfill this requirement, except that 903 Poly1305 is often used in communications protocols, so the receiver 904 should know the key. Pseudo-random number generation such as by 905 encrypting a counter is acceptable. Using ChaCha with a secret key 906 and a nonce is also acceptable. 908 The algorithms presented here were designed to be easy to implement 909 in constant time to avoid side-channel vulnerabilities. The 910 operations used in ChaCha20 are all additions, XORs, and fixed 911 rotations. All of these can and should be implemented in constant 912 time. Access to offsets into the ChaCha state and the number of 913 operations do not depend on any property of the key, eliminating the 914 chance of information about the key leaking through the timing of 915 cache misses. 917 For Poly1305, the operations are addition, multiplication and 918 modulus, all on >128-bit numbers. This can be done in constant time, 919 but a naive implementation (such as using some generic big number 920 library) will not be constant time. For example, if the 921 multiplication is performed as a separate operation from the modulus, 922 the result will some times be under 2^256 and some times be above 923 2^256. Implementers should be careful about timing side-channels for 924 Poly1305 by using the appropriate implementation of these operations. 926 5. IANA Considerations 928 There are no IANA considerations for this document. 930 6. Acknowledgements 932 ChaCha20 and Poly1305 were invented by Daniel J. Bernstein. The AEAD 933 construction and the method of creating the one-time poly1305 key 934 were invented by Adam Langley. 936 Thanks to Robert Ransom, Watson Ladd, Stefan Buhler, and kenny 937 patterson for their helpful comments and explanations. Thanks to 938 Niels Moeller for suggesting the more efficient AEAD construction in 939 this document. Special thanks to Ilari Liusvaara for providing extra 940 test vectors, helpful comments, and for being the first to attempt an 941 implementation from this draft. 943 7. References 944 7.1. Normative References 946 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 947 Requirement Levels", BCP 14, RFC 2119, March 1997. 949 [chacha] Bernstein, D., "ChaCha, a variant of Salsa20", Jan 2008. 951 [poly1305] 952 Bernstein, D., "The Poly1305-AES message-authentication 953 code", Mar 2005. 955 7.2. Informative References 957 [AE] Bellare, M. and C. Namprempre, "Authenticated Encryption: 958 Relations among notions and analysis of the generic 959 composition paradigm", 960 . 962 [FIPS-197] 963 National Institute of Standards and Technology, "Advanced 964 Encryption Standard (AES)", FIPS PUB 197, November 2001. 966 [FIPS-46] National Institute of Standards and Technology, "Data 967 Encryption Standard", FIPS PUB 46-2, December 1993, 968 . 970 [LatinDances] 971 Aumasson, J., Fischer, S., Khazaei, S., Meier, W., and C. 972 Rechberger, "New Features of Latin Dances: Analysis of 973 Salsa, ChaCha, and Rumba", Dec 2007. 975 [NaCl] Bernstein, D., Lange, T., and P. Schwabe, "NaCl: 976 Networking and Cryptography library", 977 . 979 [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 980 384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007. 982 [RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated 983 Encryption", RFC 5116, January 2008. 985 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 986 "Internet Key Exchange Protocol Version 2 (IKEv2)", 987 RFC 5996, September 2010. 989 [Zhenqing2012] 990 Zhenqing, S., Bin, Z., Dengguo, F., and W. Wenling, 991 "Improved key recovery attacks on reduced-round salsa20 992 and chacha", 2012. 994 [poly1305_donna] 995 Floodyberry, A., "Poly1305-donna", 996 . 998 [standby-cipher] 999 McGrew, D., Grieco, A., and Y. Sheffer, "Selection of 1000 Future Cryptographic Standards", 1001 draft-mcgrew-standby-cipher (work in progress). 1003 Appendix A. Additional Test Vectors 1005 The sub-sections of this appendix contain more test vectors for the 1006 algorithms in the sub-sections of Section 2. 1008 A.1. The ChaCha20 Block Functions 1010 Test Vector #1: 1011 ============== 1013 Key: 1014 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1015 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1017 Nonce: 1018 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1020 Block Counter = 0 1022 ChaCha State at the end 1023 ade0b876 903df1a0 e56a5d40 28bd8653 1024 b819d2bd 1aed8da0 ccef36a8 c70d778b 1025 7c5941da 8d485751 3fe02477 374ad8b8 1026 f4b8436a 1ca11815 69b687c3 8665eeb2 1028 Keystream: 1029 000 76 b8 e0 ad a0 f1 3d 90 40 5d 6a e5 53 86 bd 28 v.....=.@]j.S..( 1030 016 bd d2 19 b8 a0 8d ed 1a a8 36 ef cc 8b 77 0d c7 .........6...w.. 1031 032 da 41 59 7c 51 57 48 8d 77 24 e0 3f b8 d8 4a 37 .AY|QWH.w$.?..J7 1032 048 6a 43 b8 f4 15 18 a1 1c c3 87 b6 69 b2 ee 65 86 jC.........i..e. 1034 Test Vector #2: 1035 ============== 1037 Key: 1038 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1039 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1041 Nonce: 1042 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1044 Block Counter = 1 1046 ChaCha State at the end 1047 bee7079f 7a385155 7c97ba98 0d082d73 1048 a0290fcb 6965e348 3e53c612 ed7aee32 1049 7621b729 434ee69c b03371d5 d539d874 1050 281fed31 45fb0a51 1f0ae1ac 6f4d794b 1052 Keystream: 1053 000 9f 07 e7 be 55 51 38 7a 98 ba 97 7c 73 2d 08 0d ....UQ8z...|s-.. 1054 016 cb 0f 29 a0 48 e3 65 69 12 c6 53 3e 32 ee 7a ed ..).H.ei..S>2.z. 1055 032 29 b7 21 76 9c e6 4e 43 d5 71 33 b0 74 d8 39 d5 ).!v..NC.q3.t.9. 1056 048 31 ed 1f 28 51 0a fb 45 ac e1 0a 1f 4b 79 4d 6f 1..(Q..E....KyMo 1058 Test Vector #3: 1059 ============== 1061 Key: 1062 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1063 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 ................ 1065 Nonce: 1066 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1068 Block Counter = 1 1070 ChaCha State at the end 1071 2452eb3a 9249f8ec 8d829d9b ddd4ceb1 1072 e8252083 60818b01 f38422b8 5aaa49c9 1073 bb00ca8e da3ba7b4 c4b592d1 fdf2732f 1074 4436274e 2561b3c8 ebdd4aa6 a0136c00 1076 Keystream: 1077 000 3a eb 52 24 ec f8 49 92 9b 9d 82 8d b1 ce d4 dd :.R$..I......... 1078 016 83 20 25 e8 01 8b 81 60 b8 22 84 f3 c9 49 aa 5a . %....`."...I.Z 1079 032 8e ca 00 bb b4 a7 3b da d1 92 b5 c4 2f 73 f2 fd ......;...../s.. 1080 048 4e 27 36 44 c8 b3 61 25 a6 4a dd eb 00 6c 13 a0 N'6D..a%.J...l.. 1082 Test Vector #4: 1083 ============== 1085 Key: 1086 000 00 ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1087 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1089 Nonce: 1090 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1092 Block Counter = 2 1094 ChaCha State at the end 1095 fb4dd572 4bc42ef1 df922636 327f1394 1096 a78dea8f 5e269039 a1bebbc1 caf09aae 1097 a25ab213 48a6b46c 1b9d9bcb 092c5be6 1098 546ca624 1bec45d5 87f47473 96f0992e 1100 Keystream: 1101 000 72 d5 4d fb f1 2e c4 4b 36 26 92 df 94 13 7f 32 r.M....K6&.....2 1102 016 8f ea 8d a7 39 90 26 5e c1 bb be a1 ae 9a f0 ca ....9.&^........ 1103 032 13 b2 5a a2 6c b4 a6 48 cb 9b 9d 1b e6 5b 2c 09 ..Z.l..H.....[,. 1104 048 24 a6 6c 54 d5 45 ec 1b 73 74 f4 87 2e 99 f0 96 $.lT.E..st...... 1106 Test Vector #5: 1107 ============== 1109 Key: 1110 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1111 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1113 Nonce: 1114 000 00 00 00 00 00 00 00 00 00 00 00 02 ............ 1116 Block Counter = 0 1118 ChaCha State at the end 1119 374dc6c2 3736d58c b904e24a cd3f93ef 1120 88228b1a 96a4dfb3 5b76ab72 c727ee54 1121 0e0e978a f3145c95 1b748ea8 f786c297 1122 99c28f5f 628314e8 398a19fa 6ded1b53 1124 Keystream: 1125 000 c2 c6 4d 37 8c d5 36 37 4a e2 04 b9 ef 93 3f cd ..M7..67J.....?. 1126 016 1a 8b 22 88 b3 df a4 96 72 ab 76 5b 54 ee 27 c7 ..".....r.v[T.'. 1127 032 8a 97 0e 0e 95 5c 14 f3 a8 8e 74 1b 97 c2 86 f7 .....\....t..... 1128 048 5f 8f c2 99 e8 14 83 62 fa 19 8a 39 53 1b ed 6d _......b...9S..m 1130 A.2. ChaCha20 Encryption 1132 Test Vector #1: 1133 ============== 1135 Key: 1136 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1137 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1139 Nonce: 1140 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1142 Initial Block Counter = 0 1144 Plaintext: 1145 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1146 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1147 032 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1148 048 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1150 Ciphertext: 1151 000 76 b8 e0 ad a0 f1 3d 90 40 5d 6a e5 53 86 bd 28 v.....=.@]j.S..( 1152 016 bd d2 19 b8 a0 8d ed 1a a8 36 ef cc 8b 77 0d c7 .........6...w.. 1153 032 da 41 59 7c 51 57 48 8d 77 24 e0 3f b8 d8 4a 37 .AY|QWH.w$.?..J7 1154 048 6a 43 b8 f4 15 18 a1 1c c3 87 b6 69 b2 ee 65 86 jC.........i..e. 1156 Test Vector #2: 1157 ============== 1159 Key: 1160 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1161 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 ................ 1163 Nonce: 1164 000 00 00 00 00 00 00 00 00 00 00 00 02 ............ 1166 Initial Block Counter = 1 1168 Plaintext: 1169 000 41 6e 79 20 73 75 62 6d 69 73 73 69 6f 6e 20 74 Any submission t 1170 016 6f 20 74 68 65 20 49 45 54 46 20 69 6e 74 65 6e o the IETF inten 1171 032 64 65 64 20 62 79 20 74 68 65 20 43 6f 6e 74 72 ded by the Contr 1172 048 69 62 75 74 6f 72 20 66 6f 72 20 70 75 62 6c 69 ibutor for publi 1173 064 63 61 74 69 6f 6e 20 61 73 20 61 6c 6c 20 6f 72 cation as all or 1174 080 20 70 61 72 74 20 6f 66 20 61 6e 20 49 45 54 46 part of an IETF 1175 096 20 49 6e 74 65 72 6e 65 74 2d 44 72 61 66 74 20 Internet-Draft 1176 112 6f 72 20 52 46 43 20 61 6e 64 20 61 6e 79 20 73 or RFC and any s 1177 128 74 61 74 65 6d 65 6e 74 20 6d 61 64 65 20 77 69 tatement made wi 1178 144 74 68 69 6e 20 74 68 65 20 63 6f 6e 74 65 78 74 thin the context 1179 160 20 6f 66 20 61 6e 20 49 45 54 46 20 61 63 74 69 of an IETF acti 1180 176 76 69 74 79 20 69 73 20 63 6f 6e 73 69 64 65 72 vity is consider 1181 192 65 64 20 61 6e 20 22 49 45 54 46 20 43 6f 6e 74 ed an "IETF Cont 1182 208 72 69 62 75 74 69 6f 6e 22 2e 20 53 75 63 68 20 ribution". Such 1183 224 73 74 61 74 65 6d 65 6e 74 73 20 69 6e 63 6c 75 statements inclu 1184 240 64 65 20 6f 72 61 6c 20 73 74 61 74 65 6d 65 6e de oral statemen 1185 256 74 73 20 69 6e 20 49 45 54 46 20 73 65 73 73 69 ts in IETF sessi 1186 272 6f 6e 73 2c 20 61 73 20 77 65 6c 6c 20 61 73 20 ons, as well as 1187 288 77 72 69 74 74 65 6e 20 61 6e 64 20 65 6c 65 63 written and elec 1188 304 74 72 6f 6e 69 63 20 63 6f 6d 6d 75 6e 69 63 61 tronic communica 1189 320 74 69 6f 6e 73 20 6d 61 64 65 20 61 74 20 61 6e tions made at an 1190 336 79 20 74 69 6d 65 20 6f 72 20 70 6c 61 63 65 2c y time or place, 1191 352 20 77 68 69 63 68 20 61 72 65 20 61 64 64 72 65 which are addre 1192 368 73 73 65 64 20 74 6f ssed to 1194 Ciphertext: 1195 000 a3 fb f0 7d f3 fa 2f de 4f 37 6c a2 3e 82 73 70 ...}../.O7l.>.sp 1196 016 41 60 5d 9f 4f 4f 57 bd 8c ff 2c 1d 4b 79 55 ec A`].OOW...,.KyU. 1197 032 2a 97 94 8b d3 72 29 15 c8 f3 d3 37 f7 d3 70 05 *....r)....7..p. 1198 048 0e 9e 96 d6 47 b7 c3 9f 56 e0 31 ca 5e b6 25 0d ....G...V.1.^.%. 1199 064 40 42 e0 27 85 ec ec fa 4b 4b b5 e8 ea d0 44 0e @B.'....KK....D. 1200 080 20 b6 e8 db 09 d8 81 a7 c6 13 2f 42 0e 52 79 50 ........./B.RyP 1201 096 42 bd fa 77 73 d8 a9 05 14 47 b3 29 1c e1 41 1c B..ws....G.)..A. 1202 112 68 04 65 55 2a a6 c4 05 b7 76 4d 5e 87 be a8 5a h.eU*....vM^...Z 1203 128 d0 0f 84 49 ed 8f 72 d0 d6 62 ab 05 26 91 ca 66 ...I..r..b..&..f 1204 144 42 4b c8 6d 2d f8 0e a4 1f 43 ab f9 37 d3 25 9d BK.m-....C..7.%. 1205 160 c4 b2 d0 df b4 8a 6c 91 39 dd d7 f7 69 66 e9 28 ......l.9...if.( 1206 176 e6 35 55 3b a7 6c 5c 87 9d 7b 35 d4 9e b2 e6 2b .5U;.l\..{5....+ 1207 192 08 71 cd ac 63 89 39 e2 5e 8a 1e 0e f9 d5 28 0f .q..c.9.^.....(. 1208 208 a8 ca 32 8b 35 1c 3c 76 59 89 cb cf 3d aa 8b 6c ..2.5.vC.. 1247 080 1a 55 32 05 57 16 ea d6 96 25 68 f8 7d 3f 3f 77 .U2.W....%h.}??w 1248 096 04 c6 a8 d1 bc d1 bf 4d 50 d6 15 4b 6d a7 31 b1 .......MP..Km.1. 1249 112 87 b5 8d fd 72 8a fa 36 75 7a 79 7a c1 88 d1 ....r..6uzyz... 1251 A.3. Poly1305 Message Authentication Code 1253 Notice how in test vector #2 r is equal to zero. The part of the 1254 Poly1305 algorithm where the accumulator is multiplied by r means 1255 that with r equal zero, the tag will be equal to s regardless of the 1256 content of the Text. Fortunately, all the proposed methods of 1257 generating r are such that getting this particular weak key is very 1258 unlikely. 1260 Test Vector #1: 1261 ============== 1263 One-time Poly1305 Key: 1264 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1265 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1267 Text to MAC: 1268 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1269 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1270 032 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1271 048 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1273 Tag: 1274 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1276 Test Vector #2: 1277 ============== 1279 One-time Poly1305 Key: 1280 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1281 016 36 e5 f6 b5 c5 e0 60 70 f0 ef ca 96 22 7a 86 3e 6.....`p...."z.> 1283 Text to MAC: 1284 000 41 6e 79 20 73 75 62 6d 69 73 73 69 6f 6e 20 74 Any submission t 1285 016 6f 20 74 68 65 20 49 45 54 46 20 69 6e 74 65 6e o the IETF inten 1286 032 64 65 64 20 62 79 20 74 68 65 20 43 6f 6e 74 72 ded by the Contr 1287 048 69 62 75 74 6f 72 20 66 6f 72 20 70 75 62 6c 69 ibutor for publi 1288 064 63 61 74 69 6f 6e 20 61 73 20 61 6c 6c 20 6f 72 cation as all or 1289 080 20 70 61 72 74 20 6f 66 20 61 6e 20 49 45 54 46 part of an IETF 1290 096 20 49 6e 74 65 72 6e 65 74 2d 44 72 61 66 74 20 Internet-Draft 1291 112 6f 72 20 52 46 43 20 61 6e 64 20 61 6e 79 20 73 or RFC and any s 1292 128 74 61 74 65 6d 65 6e 74 20 6d 61 64 65 20 77 69 tatement made wi 1293 144 74 68 69 6e 20 74 68 65 20 63 6f 6e 74 65 78 74 thin the context 1294 160 20 6f 66 20 61 6e 20 49 45 54 46 20 61 63 74 69 of an IETF acti 1295 176 76 69 74 79 20 69 73 20 63 6f 6e 73 69 64 65 72 vity is consider 1296 192 65 64 20 61 6e 20 22 49 45 54 46 20 43 6f 6e 74 ed an "IETF Cont 1297 208 72 69 62 75 74 69 6f 6e 22 2e 20 53 75 63 68 20 ribution". Such 1298 224 73 74 61 74 65 6d 65 6e 74 73 20 69 6e 63 6c 75 statements inclu 1299 240 64 65 20 6f 72 61 6c 20 73 74 61 74 65 6d 65 6e de oral statemen 1300 256 74 73 20 69 6e 20 49 45 54 46 20 73 65 73 73 69 ts in IETF sessi 1301 272 6f 6e 73 2c 20 61 73 20 77 65 6c 6c 20 61 73 20 ons, as well as 1302 288 77 72 69 74 74 65 6e 20 61 6e 64 20 65 6c 65 63 written and elec 1303 304 74 72 6f 6e 69 63 20 63 6f 6d 6d 75 6e 69 63 61 tronic communica 1304 320 74 69 6f 6e 73 20 6d 61 64 65 20 61 74 20 61 6e tions made at an 1305 336 79 20 74 69 6d 65 20 6f 72 20 70 6c 61 63 65 2c y time or place, 1306 352 20 77 68 69 63 68 20 61 72 65 20 61 64 64 72 65 which are addre 1307 368 73 73 65 64 20 74 6f ssed to 1309 Tag: 1310 000 36 e5 f6 b5 c5 e0 60 70 f0 ef ca 96 22 7a 86 3e 6.....`p...."z.> 1311 Test Vector #3: 1312 ============== 1314 One-time Poly1305 Key: 1315 000 36 e5 f6 b5 c5 e0 60 70 f0 ef ca 96 22 7a 86 3e 6.....`p...."z.> 1316 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1318 Text to MAC: 1319 000 41 6e 79 20 73 75 62 6d 69 73 73 69 6f 6e 20 74 Any submission t 1320 016 6f 20 74 68 65 20 49 45 54 46 20 69 6e 74 65 6e o the IETF inten 1321 032 64 65 64 20 62 79 20 74 68 65 20 43 6f 6e 74 72 ded by the Contr 1322 048 69 62 75 74 6f 72 20 66 6f 72 20 70 75 62 6c 69 ibutor for publi 1323 064 63 61 74 69 6f 6e 20 61 73 20 61 6c 6c 20 6f 72 cation as all or 1324 080 20 70 61 72 74 20 6f 66 20 61 6e 20 49 45 54 46 part of an IETF 1325 096 20 49 6e 74 65 72 6e 65 74 2d 44 72 61 66 74 20 Internet-Draft 1326 112 6f 72 20 52 46 43 20 61 6e 64 20 61 6e 79 20 73 or RFC and any s 1327 128 74 61 74 65 6d 65 6e 74 20 6d 61 64 65 20 77 69 tatement made wi 1328 144 74 68 69 6e 20 74 68 65 20 63 6f 6e 74 65 78 74 thin the context 1329 160 20 6f 66 20 61 6e 20 49 45 54 46 20 61 63 74 69 of an IETF acti 1330 176 76 69 74 79 20 69 73 20 63 6f 6e 73 69 64 65 72 vity is consider 1331 192 65 64 20 61 6e 20 22 49 45 54 46 20 43 6f 6e 74 ed an "IETF Cont 1332 208 72 69 62 75 74 69 6f 6e 22 2e 20 53 75 63 68 20 ribution". Such 1333 224 73 74 61 74 65 6d 65 6e 74 73 20 69 6e 63 6c 75 statements inclu 1334 240 64 65 20 6f 72 61 6c 20 73 74 61 74 65 6d 65 6e de oral statemen 1335 256 74 73 20 69 6e 20 49 45 54 46 20 73 65 73 73 69 ts in IETF sessi 1336 272 6f 6e 73 2c 20 61 73 20 77 65 6c 6c 20 61 73 20 ons, as well as 1337 288 77 72 69 74 74 65 6e 20 61 6e 64 20 65 6c 65 63 written and elec 1338 304 74 72 6f 6e 69 63 20 63 6f 6d 6d 75 6e 69 63 61 tronic communica 1339 320 74 69 6f 6e 73 20 6d 61 64 65 20 61 74 20 61 6e tions made at an 1340 336 79 20 74 69 6d 65 20 6f 72 20 70 6c 61 63 65 2c y time or place, 1341 352 20 77 68 69 63 68 20 61 72 65 20 61 64 64 72 65 which are addre 1342 368 73 73 65 64 20 74 6f ssed to 1344 Tag: 1345 000 f3 47 7e 7c d9 54 17 af 89 a6 b8 79 4c 31 0c f0 .G~|.T.....yL1.. 1347 Test Vector #4: 1348 ============== 1350 One-time Poly1305 Key: 1351 000 1c 92 40 a5 eb 55 d3 8a f3 33 88 86 04 f6 b5 f0 ..@..U...3...... 1352 016 47 39 17 c1 40 2b 80 09 9d ca 5c bc 20 70 75 c0 G9..@+....\. pu. 1354 Text to MAC: 1355 000 27 54 77 61 73 20 62 72 69 6c 6c 69 67 2c 20 61 'Twas brillig, a 1356 016 6e 64 20 74 68 65 20 73 6c 69 74 68 79 20 74 6f nd the slithy to 1357 032 76 65 73 0a 44 69 64 20 67 79 72 65 20 61 6e 64 ves.Did gyre and 1358 048 20 67 69 6d 62 6c 65 20 69 6e 20 74 68 65 20 77 gimble in the w 1359 064 61 62 65 3a 0a 41 6c 6c 20 6d 69 6d 73 79 20 77 abe:.All mimsy w 1360 080 65 72 65 20 74 68 65 20 62 6f 72 6f 67 6f 76 65 ere the borogove 1361 096 73 2c 0a 41 6e 64 20 74 68 65 20 6d 6f 6d 65 20 s,.And the mome 1362 112 72 61 74 68 73 20 6f 75 74 67 72 61 62 65 2e raths outgrabe. 1364 Tag: 1365 000 45 41 66 9a 7e aa ee 61 e7 08 dc 7c bc c5 eb 62 EAf.~..a...|...b 1367 Test Vector #5: If one uses 130-bit partial reduction, does the code 1368 handle the case where partially reduced final result is not fully 1369 reduced? 1371 R: 1372 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1373 S: 1374 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1375 data: 1376 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1377 tag: 1378 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1380 Test Vector #6: What happens if addition of s overflows modulo 2^128? 1382 R: 1383 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1384 S: 1385 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1386 data: 1387 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1388 tag: 1389 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1390 Test Vector #7: What happens if data limb is all ones and there is 1391 carry from lower limb? 1393 R: 1394 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1395 S: 1396 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1397 data: 1398 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1399 F0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1400 11 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1401 tag: 1402 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1404 Test Vector #8: What happens if final result from polynomial part is 1405 exactly 2^130-5? 1407 R: 1408 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1409 S: 1410 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1411 data: 1412 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1413 FB FE FE FE FE FE FE FE FE FE FE FE FE FE FE FE 1414 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 1415 tag: 1416 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1418 Test Vector #9: What happens if final result from polynomial part is 1419 exactly 2^130-6? 1421 R: 1422 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1423 S: 1424 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1425 data: 1426 FD FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1427 tag: 1428 FA FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 1429 Test Vector #10: What happens if 5*H+L-type reduction produces 131- 1430 bit intermediate result? 1432 R: 1433 01 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 1434 S: 1435 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1436 data: 1437 E3 35 94 D7 50 5E 43 B9 00 00 00 00 00 00 00 00 1438 33 94 D7 50 5E 43 79 CD 01 00 00 00 00 00 00 00 1439 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1440 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1441 tag: 1442 14 00 00 00 00 00 00 00 55 00 00 00 00 00 00 00 1444 Test Vector #11: What happens if 5*H+L-type reduction produces 131- 1445 bit final result? 1447 R: 1448 01 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 1449 S: 1450 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1451 data: 1452 E3 35 94 D7 50 5E 43 B9 00 00 00 00 00 00 00 00 1453 33 94 D7 50 5E 43 79 CD 01 00 00 00 00 00 00 00 1454 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1455 tag: 1456 13 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1458 A.4. Poly1305 Key Generation Using ChaCha20 1460 Test Vector #1: 1461 ============== 1463 The key: 1464 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1465 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1467 The nonce: 1468 000 00 00 00 00 00 00 00 00 00 00 00 00 ............ 1470 Poly1305 one-time key: 1471 000 76 b8 e0 ad a0 f1 3d 90 40 5d 6a e5 53 86 bd 28 v.....=.@]j.S..( 1472 016 bd d2 19 b8 a0 8d ed 1a a8 36 ef cc 8b 77 0d c7 .........6...w.. 1474 Test Vector #2: 1475 ============== 1477 The key: 1478 000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1479 016 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 ................ 1481 The nonce: 1482 000 00 00 00 00 00 00 00 00 00 00 00 02 ............ 1484 Poly1305 one-time key: 1485 000 ec fa 25 4f 84 5f 64 74 73 d3 cb 14 0d a9 e8 76 ..%O._dts......v 1486 016 06 cb 33 06 6c 44 7b 87 bc 26 66 dd e3 fb b7 39 ..3.lD{..&f....9 1488 Test Vector #3: 1489 ============== 1491 The key: 1492 000 1c 92 40 a5 eb 55 d3 8a f3 33 88 86 04 f6 b5 f0 ..@..U...3...... 1493 016 47 39 17 c1 40 2b 80 09 9d ca 5c bc 20 70 75 c0 G9..@+....\. pu. 1495 The nonce: 1496 000 00 00 00 00 00 00 00 00 00 00 00 02 ............ 1498 Poly1305 one-time key: 1499 000 96 5e 3b c6 f9 ec 7e d9 56 08 08 f4 d2 29 f9 4b .^;...~.V....).K 1500 016 13 7f f2 75 ca 9b 3f cb dd 59 de aa d2 33 10 ae ...u..?..Y...3.. 1502 A.5. ChaCha20-Poly1305 AEAD Decryption 1504 Below we'll see decrypting a message. We receive a ciphertext, a 1505 nonce, and a tag. We know the key. We will check the tag, and then 1506 (assuming that it validates) decrypt the ciphertext. In this 1507 particular protocol, we'll assume that there is no padding of the 1508 plaintext. 1510 The key: 1511 000 1c 92 40 a5 eb 55 d3 8a f3 33 88 86 04 f6 b5 f0 ..@..U...3...... 1512 016 47 39 17 c1 40 2b 80 09 9d ca 5c bc 20 70 75 c0 G9..@+....\. pu. 1514 Ciphertext: 1515 000 64 a0 86 15 75 86 1a f4 60 f0 62 c7 9b e6 43 bd d...u...`.b...C. 1516 016 5e 80 5c fd 34 5c f3 89 f1 08 67 0a c7 6c 8c b2 ^.\.4\....g..l.. 1517 032 4c 6c fc 18 75 5d 43 ee a0 9e e9 4e 38 2d 26 b0 Ll..u]C....N8-&. 1518 048 bd b7 b7 3c 32 1b 01 00 d4 f0 3b 7f 35 58 94 cf ...<2.....;.5X.. 1519 064 33 2f 83 0e 71 0b 97 ce 98 c8 a8 4a bd 0b 94 81 3/..q......J.... 1520 080 14 ad 17 6e 00 8d 33 bd 60 f9 82 b1 ff 37 c8 55 ...n..3.`....7.U 1521 096 97 97 a0 6e f4 f0 ef 61 c1 86 32 4e 2b 35 06 38 ...n...a..2N+5.8 1522 112 36 06 90 7b 6a 7c 02 b0 f9 f6 15 7b 53 c8 67 e4 6..{j|.....{S.g. 1523 128 b9 16 6c 76 7b 80 4d 46 a5 9b 52 16 cd e7 a4 e9 ..lv{.MF..R..... 1524 144 90 40 c5 a4 04 33 22 5e e2 82 a1 b0 a0 6c 52 3e .@...3"^.....lR> 1525 160 af 45 34 d7 f8 3f a1 15 5b 00 47 71 8c bc 54 6a .E4..?..[.Gq..Tj 1526 176 0d 07 2b 04 b3 56 4e ea 1b 42 22 73 f5 48 27 1a ..+..VN..B"s.H'. 1527 192 0b b2 31 60 53 fa 76 99 19 55 eb d6 31 59 43 4e ..1`S.v..U..1YCN 1528 208 ce bb 4e 46 6d ae 5a 10 73 a6 72 76 27 09 7a 10 ..NFm.Z.s.rv'.z. 1529 224 49 e6 17 d9 1d 36 10 94 fa 68 f0 ff 77 98 71 30 I....6...h..w.q0 1530 240 30 5b ea ba 2e da 04 df 99 7b 71 4d 6c 6f 2c 29 0[.......{qMlo,) 1531 256 a6 ad 5c b4 02 2b 02 70 9b ..\..+.p. 1533 The nonce: 1534 000 00 00 00 00 01 02 03 04 05 06 07 08 ............ 1536 The AAD: 1537 000 f3 33 88 86 00 00 00 00 00 00 4e 91 .3........N. 1539 Received Tag: 1540 000 ee ad 9d 67 89 0c bb 22 39 23 36 fe a1 85 1f 38 ...g..."9#6....8 1541 First, we calculate the one-time Poly1305 key 1543 @@@ ChaCha state with key set up 1544 61707865 3320646e 79622d32 6b206574 1545 a540921c 8ad355eb 868833f3 f0b5f604 1546 c1173947 09802b40 bc5cca9d c0757020 1547 00000000 00000000 04030201 08070605 1549 @@@ ChaCha state after 20 rounds 1550 a94af0bd 89dee45c b64bb195 afec8fa1 1551 508f4726 63f554c0 1ea2c0db aa721526 1552 11b1e514 a0bacc0f 828a6015 d7825481 1553 e8a4a850 d9dcbbd6 4c2de33a f8ccd912 1555 @@@ out bytes: 1556 bd:f0:4a:a9:5c:e4:de:89:95:b1:4b:b6:a1:8f:ec:af: 1557 26:47:8f:50:c0:54:f5:63:db:c0:a2:1e:26:15:72:aa 1559 Poly1305 one-time key: 1560 000 bd f0 4a a9 5c e4 de 89 95 b1 4b b6 a1 8f ec af ..J.\.....K..... 1561 016 26 47 8f 50 c0 54 f5 63 db c0 a2 1e 26 15 72 aa &G.P.T.c....&.r. 1563 Next, we construct the AEAD buffer 1565 Poly1305 Input: 1566 000 f3 33 88 86 00 00 00 00 00 00 4e 91 00 00 00 00 .3........N..... 1567 016 64 a0 86 15 75 86 1a f4 60 f0 62 c7 9b e6 43 bd d...u...`.b...C. 1568 032 5e 80 5c fd 34 5c f3 89 f1 08 67 0a c7 6c 8c b2 ^.\.4\....g..l.. 1569 048 4c 6c fc 18 75 5d 43 ee a0 9e e9 4e 38 2d 26 b0 Ll..u]C....N8-&. 1570 064 bd b7 b7 3c 32 1b 01 00 d4 f0 3b 7f 35 58 94 cf ...<2.....;.5X.. 1571 080 33 2f 83 0e 71 0b 97 ce 98 c8 a8 4a bd 0b 94 81 3/..q......J.... 1572 096 14 ad 17 6e 00 8d 33 bd 60 f9 82 b1 ff 37 c8 55 ...n..3.`....7.U 1573 112 97 97 a0 6e f4 f0 ef 61 c1 86 32 4e 2b 35 06 38 ...n...a..2N+5.8 1574 128 36 06 90 7b 6a 7c 02 b0 f9 f6 15 7b 53 c8 67 e4 6..{j|.....{S.g. 1575 144 b9 16 6c 76 7b 80 4d 46 a5 9b 52 16 cd e7 a4 e9 ..lv{.MF..R..... 1576 160 90 40 c5 a4 04 33 22 5e e2 82 a1 b0 a0 6c 52 3e .@...3"^.....lR> 1577 176 af 45 34 d7 f8 3f a1 15 5b 00 47 71 8c bc 54 6a .E4..?..[.Gq..Tj 1578 192 0d 07 2b 04 b3 56 4e ea 1b 42 22 73 f5 48 27 1a ..+..VN..B"s.H'. 1579 208 0b b2 31 60 53 fa 76 99 19 55 eb d6 31 59 43 4e ..1`S.v..U..1YCN 1580 224 ce bb 4e 46 6d ae 5a 10 73 a6 72 76 27 09 7a 10 ..NFm.Z.s.rv'.z. 1581 240 49 e6 17 d9 1d 36 10 94 fa 68 f0 ff 77 98 71 30 I....6...h..w.q0 1582 256 30 5b ea ba 2e da 04 df 99 7b 71 4d 6c 6f 2c 29 0[.......{qMlo,) 1583 272 a6 ad 5c b4 02 2b 02 70 9b 00 00 00 00 00 00 00 ..\..+.p........ 1584 288 0c 00 00 00 00 00 00 00 09 01 00 00 00 00 00 00 ................ 1586 We calculate the Poly1305 tag and find that it matches 1588 Calculated Tag: 1589 000 ee ad 9d 67 89 0c bb 22 39 23 36 fe a1 85 1f 38 ...g..."9#6....8 1591 Finally, we decrypt the ciphertext 1593 Plaintext:: 1594 000 49 6e 74 65 72 6e 65 74 2d 44 72 61 66 74 73 20 Internet-Drafts 1595 016 61 72 65 20 64 72 61 66 74 20 64 6f 63 75 6d 65 are draft docume 1596 032 6e 74 73 20 76 61 6c 69 64 20 66 6f 72 20 61 20 nts valid for a 1597 048 6d 61 78 69 6d 75 6d 20 6f 66 20 73 69 78 20 6d maximum of six m 1598 064 6f 6e 74 68 73 20 61 6e 64 20 6d 61 79 20 62 65 onths and may be 1599 080 20 75 70 64 61 74 65 64 2c 20 72 65 70 6c 61 63 updated, replac 1600 096 65 64 2c 20 6f 72 20 6f 62 73 6f 6c 65 74 65 64 ed, or obsoleted 1601 112 20 62 79 20 6f 74 68 65 72 20 64 6f 63 75 6d 65 by other docume 1602 128 6e 74 73 20 61 74 20 61 6e 79 20 74 69 6d 65 2e nts at any time. 1603 144 20 49 74 20 69 73 20 69 6e 61 70 70 72 6f 70 72 It is inappropr 1604 160 69 61 74 65 20 74 6f 20 75 73 65 20 49 6e 74 65 iate to use Inte 1605 176 72 6e 65 74 2d 44 72 61 66 74 73 20 61 73 20 72 rnet-Drafts as r 1606 192 65 66 65 72 65 6e 63 65 20 6d 61 74 65 72 69 61 eference materia 1607 208 6c 20 6f 72 20 74 6f 20 63 69 74 65 20 74 68 65 l or to cite the 1608 224 6d 20 6f 74 68 65 72 20 74 68 61 6e 20 61 73 20 m other than as 1609 240 2f e2 80 9c 77 6f 72 6b 20 69 6e 20 70 72 6f 67 /...work in prog 1610 256 72 65 73 73 2e 2f e2 80 9d ress./... 1612 Authors' Addresses 1614 Yoav Nir 1615 Check Point Software Technologies Ltd. 1616 5 Hasolelim st. 1617 Tel Aviv 6789735 1618 Israel 1620 Email: ynir.ietf@gmail.com 1622 Adam Langley 1623 Google Inc 1625 Email: agl@google.com