Network Working Group M. Jenkins
Internet Draft National Security Agency
Intended Status: Informational M. Peck
Expires: January 6, 2017 The MITRE Corporation
K. Burgin
July 5, 2016
AES Encryption with HMAC-SHA2 for Kerberos 5
draft-ietf-kitten-aes-cts-hmac-sha2-10
Abstract
This document specifies two encryption types and two corresponding
checksum types for Kerberos 5. The new types use AES in CTS mode
(CBC mode with ciphertext stealing) for confidentiality and HMAC with
a SHA-2 hash for integrity.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 6, 2017.
Copyright and License Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Key Representation . . . . . . . . . . . . . . . . . 3
3. Key Derivation Function . . . . . . . . . . . . . . . . . . . 3
4. Key Generation from Pass Phrases . . . . . . . . . . . . . . . 4
5. Kerberos Algorithm Protocol Parameters . . . . . . . . . . . . 5
6. Checksum Parameters . . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8.1. Random Values in Salt Strings . . . . . . . . . . . . . . 9
8.2. Algorithm Rationale . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 10
Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
This document defines two encryption types and two corresponding
checksum types for Kerberos 5 using AES with 128-bit or 256-bit keys.
To avoid ciphertext expansion, we use a variation of the CBC-CS3 mode
defined in [SP800-38A+], also referred to as ciphertext stealing or
CTS mode. The new types conform to the framework specified in
[RFC3961], but do not use the simplified profile.
The encryption and checksum types defined in this document are
intended to support environments that desire to use SHA-256 or SHA-
384 (defined in [FIPS180]) as the hash algorithm. Differences
between the encryption and checksum types defined in this document
and the pre-existing Kerberos AES encryption and checksum types
specified in [RFC3962] are:
* The pseudorandom function used by PBKDF2 is HMAC-SHA-256 or HMAC-
SHA-384 (HMAC is defined in [RFC2104]).
* A key derivation function from [SP800-108] using the SHA-256 or
SHA-384 hash algorithm is used to produce keys for encryption,
integrity protection, and checksum operations.
* The HMAC is calculated over the cipherstate concatenated with the
AES output, instead of being calculated over the confounder and
plaintext. This allows the message receiver to verify the
integrity of the message before decrypting the message.
* The HMAC algorithm uses the SHA-256 or SHA-384 hash algorithm for
integrity protection and checksum operations.
2. Protocol Key Representation
The AES key space is dense, so we can use random or pseudorandom
octet strings directly as keys. The byte representation for the key
is described in [FIPS197], where the first bit of the bit string is
the high bit of the first byte of the byte string (octet string).
3. Key Derivation Function
We use a key derivation function from Section 5.1 of [SP800-108]
which uses the HMAC algorithm as the PRF.
function KDF-HMAC-SHA2(key, label, [context,] k):
k-truncate(K1)
where the value of K1 is computed as below.
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key: The source of entropy from which subsequent keys are derived
(this is known as Ki in [SP800-108]).
label: An octet string describing the intended usage of the derived
key.
context: This parameter is optional. An octet string containing the
information related to the derived keying material. It may include
identities of parties who are deriving and/or using the derived key
material and, optionally, a nonce known by the parties who derive the
keys.
k: Length in bits of the key to be outputted, expressed in big-endian
binary representation in 4 bytes (this is called L in [SP800-108]).
Specifically, k=128 is represented as 0x00000080, 192 as 0x000000C0,
256 as 0x00000100, and 384 as 0x00000180.
When the encryption type is aes128-cts-hmac-sha256-128, k must be no
greater than 256. When the encryption type is aes256-cts-hmac-sha384-
192, k must be no greater than 384.
The k-truncate function is defined in [RFC3961], Section 5.1. It
returns the 'k' leftmost bits of the bitstring input.
In all computations in this document, | indicates concatenation.
When the encryption type is aes128-cts-hmac-sha256-128, then K1 is
computed as follows:
If the context parameter is not present:
K1 = HMAC-SHA-256(key, 0x00000001 | label | 0x00 | k)
If the context parameter is present:
K1 = HMAC-SHA-256(key, 0x00000001 | label | 0x00 | context | k)
When the encryption type is aes256-cts-hmac-sha384-192, then K1 is
computed as follows:
If the context parameter is not present:
K1 = HMAC-SHA-384(key, 0x00000001 | label | 0x00 | k)
If the context parameter is present:
K1 = HMAC-SHA-384(key, 0x00000001 | label | 0x00 | context | k)
In the definitions of K1 above, '0x00000001' is the i parameter (the
iteration counter) from Section 5.1 of [SP800-108].
4. Key Generation from Pass Phrases
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As defined below, the string-to-key function uses PBKDF2 [RFC2898]
and KDF-HMAC-SHA2 to derive the base-key from a passphrase and salt.
The string-to-key parameter string is four octets indicating an
unsigned number in big-endian order, consistent with [RFC3962],
except that the default is decimal 32768 if the parameter is not
specified.
To ensure that different long-term base-keys are used with different
enctypes, we prepend the enctype name to the salt, separated by a
null byte. The enctype-name is "aes128-cts-hmac-sha256-128" or
"aes256-cts-hmac-sha384-192" (without the quotes).
The user's long-term base-key is derived as follows:
iter_count = string-to-key parameter, default is decimal 32768
saltp = enctype-name | 0x00 | salt
tkey = random-to-key(PBKDF2(passphrase, saltp,
iter_count, keylength))
base-key = random-to-key(KDF-HMAC-SHA2(tkey, "kerberos",
keylength))
where "kerberos" is the octet-string 0x6B65726265726F73.
where PBKDF2 is the function of that name from RFC 2898, the
pseudorandom function used by PBKDF2 is HMAC-SHA-256 when the enctype
is "aes128-cts-hmac-sha256-128" and HMAC-SHA-384 when the enctype is
"aes256-cts-hmac-sha384-192", the value for keylength is the AES key
length (128 or 256 bits), and the algorithm KDF-HMAC-SHA2 is defined
in Section 3.
5. Kerberos Algorithm Protocol Parameters
The RFC 3961 cipher state that maintains cryptographic state across
different encryption operations using the same key is used as the
formal initialization vector (IV) input into CBC-CS3. The plaintext
is prepended with a 16-octet random nonce generated by the message
originator, known as a confounder.
The ciphertext is a concatenation of the output of AES in CBC-CS3
mode and the HMAC of the cipher state concatenated with the AES
output. The HMAC is computed using either SHA-256 or SHA-384
depending on the encryption type. The output of HMAC-SHA-256 is
truncated to 128 bits and the output of HMAC-SHA-384 is truncated to
192 bits. Sample test vectors are given in Appendix A.
Decryption is performed by removing the HMAC, verifying the HMAC
against the cipher state concatenated with the ciphertext, and then
decrypting the ciphertext if the HMAC is correct. Finally, the first
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16 octets of the decryption output (the confounder) is discarded, and
the remainder is returned as the plaintext decryption output.
The following parameters apply to the encryption types aes128-cts-
hmac-sha256-128 and aes256-cts-hmac-sha384-192.
protocol key format: as defined in Section 2.
specific key structure: three derived keys: { Kc, Ke, Ki }.
Kc: the checksum key, inputted into HMAC to provide the checksum
mechanism defined in Section 6.
Ke: the encryption key, inputted into AES encryption and decryption
as defined in "encryption function" and "decryption function" below.
Ki: the integrity key, inputted into HMAC to provide authenticated
encryption as defined in "encryption function" and "decryption
function" below.
required checksum mechanism: as defined in Section 6.
key-generation seed length: key size (128 or 256 bits).
string-to-key function: as defined in Section 4.
default string-to-key parameters: decimal 32768.
random-to-key function: identity function.
key-derivation function: KDF-HMAC-SHA2 as defined in Section 3. The
key usage number is expressed as four octets in big-endian order.
If the enctype is aes128-cts-hmac-sha256-128:
Kc = KDF-HMAC-SHA2(base-key, usage | 0x99, 128)
Ke = KDF-HMAC-SHA2(base-key, usage | 0xAA, 128)
Ki = KDF-HMAC-SHA2(base-key, usage | 0x55, 128)
If the enctype is aes256-cts-hmac-sha384-192:
Kc = KDF-HMAC-SHA2(base-key, usage | 0x99, 192)
Ke = KDF-HMAC-SHA2(base-key, usage | 0xAA, 256)
Ki = KDF-HMAC-SHA2(base-key, usage | 0x55, 192)
cipher state: a 128-bit CBC initialization vector derived from a
previous (if any) ciphertext using the same encryption key, as
specified below.
initial cipher state: all bits zero.
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encryption function: as follows, where E() is AES encryption in
CBC-CS3 mode, and h is the size of truncated HMAC (128 bits or
192 bits as described above).
N = random nonce of length 128 bits (the AES block size)
IV = cipher state
C = E(Ke, N | plaintext, IV)
H = HMAC(Ki, IV | C)
ciphertext = C | H[1..h]
Steps to compute the 128-bit cipher state:
L = length of C in bits
portion C into 128-bit blocks, placing any remainder
of less than 128 bits into a final block
if L == 128: cipher state = C
else if L mod 128 > 0: cipher state = last full (128-bit)
block of C (the
next-to-last block)
else if L mod 128 == 0: cipher state = next-to-last block
of C
(note that L will never be less than 128 because of the
presence of N in the encryption input)
decryption function: as follows, where D() is AES decryption in
CBC-CS3 mode, and h is the size of truncated HMAC.
(C, H) = ciphertext (Note: H is the last h bits of the ciphertext)
IV = cipher state
if H != HMAC(Ki, IV | C)[1..h]
stop, report error
(N, P) = D(Ke, C, IV)
Note: N is set to the first block of the decryption output,
P is set to the rest of the output.
cipher state = same as described above in encryption function
pseudo-random function:
If the enctype is aes128-cts-hmac-sha256-128:
PRF = KDF-HMAC-SHA2(input-key, "prf", octet-string, 256)
If the enctype is aes256-cts-hmac-sha384-192:
PRF = KDF-HMAC-SHA2(input-key, "prf", octet-string, 384)
where "prf" is the octet-string 0x707266
6. Checksum Parameters
The following parameters apply to the checksum types hmac-sha256-128-
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aes128 and hmac-sha384-192-aes256, which are the associated checksums
for aes128-cts-hmac-sha256-128 and aes256-cts-hmac-sha384-192,
respectively.
associated cryptosystem: aes128-cts-hmac-sha256-128 or aes256-cts-
hmac-sha384-192 as appropriate.
get_mic: HMAC(Kc, message)[1..h].
where h is 128 bits for checksum type hmac-sha256-128-aes128
and 192 bits for checksum type hmac-sha384-192-aes256
verify_mic: get_mic and compare.
7. IANA Considerations
IANA is requested to assign:
Encryption type numbers for aes128-cts-hmac-sha256-128 and
aes256-cts-hmac-sha384-192 in the Kerberos Encryption Type Numbers
registry.
Etype Encryption type Reference
----- --------------- ---------
TBD1 aes128-cts-hmac-sha256-128 [this document]
TBD2 aes256-cts-hmac-sha384-192 [this document]
Checksum type numbers for hmac-sha256-128-aes128 and hmac-sha384-192-
aes256 in the Kerberos Checksum Type Numbers registry.
Sumtype Checksum type Size Reference
------- ------------- ---- ---------
TBD3 hmac-sha256-128-aes128 16 [this document]
TBD4 hmac-sha384-192-aes256 24 [this document]
8. Security Considerations
This specification requires implementations to generate random
values. The use of inadequate pseudo-random number generators
(PRNGs) can result in little or no security. The generation of
quality random numbers is difficult. [RFC4086] offers random number
generation guidance.
This document specifies a mechanism for generating keys from
passphrases or passwords. The use of PBKDF2, a salt, and a large
iteration count adds some resistance to off-line dictionary attacks
by passive eavesdroppers. Salting prevents rainbow table attacks,
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while large iteration counts slow password guess attempts.
Nonetheless, it is important to choose strong passphrases. Use of
other Kerberos extensions that protect against off-line dictionary
attacks should also be considered.
The NIST guidance in section 5.3 of [SP800-38A], requiring that CBC
initialization vectors be unpredictable, is satisfied by the use of a
random confounder as the first block of plaintext. The confounder
fills the cryptographic role typically played by an initialization
vector. This approach was chosen to align with other Kerberos
cryptosystem approaches.
8.1. Random Values in Salt Strings
NIST guidance in Section 5.1 of [SP800-132] requires at least 128
bits of the salt to be randomly generated. The string-to-key function
as defined in [RFC3961] requires the salt to be valid UTF-8 strings.
Not every 128-bit random string will be valid UTF-8, so a UTF-8
compatible encoding would be needed to encapsulate the random bits.
However, using a salt containing a random portion may have the
following issues with some implementations:
* Cross-realm krbtgt keys are typically managed by entering the
same password at two KDCs to get the same keys. If each KDC uses
a random salt, they won't have the same keys.
* Random salts may interfere with password history checking.
8.2. Algorithm Rationale
This document has been written to be consistent with common
implementations of AES and SHA-2. The encryption and hash algorithm
sizes have been chosen to create a consistent level of protection,
with consideration to implementation efficiencies. So, for instance,
SHA-384, which would normally be matched to AES-192, is instead
matched to AES-256 to leverage the fact that there are efficient
hardware implementations of AES-256. Note that, as indicated by the
enc-type name "aes256-cts-hmac-sha384-192", the truncation of the
HMAC-SHA-384 output to 192-bits results in an overall 192-bit level
of security.
9. Acknowledgements
Kelley Burgin was employed at the National Security Agency during
much of the work on this document.
10. References
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10.1. Normative References
[RFC2104] Krawczyk, H. et al., "HMAC: Keyed-Hashing for Message
Authentication", RFC 2104, February 1997.
[RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification Version 2.0", RFC 2898, September 2000.
[RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
Kerberos 5", RFC 3961, February 2005.
[RFC3962] Raeburn, K., "Advanced Encryption Standard (AES)
Encryption for Kerberos 5", RFC 3962, February 2005.
[FIPS180] National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-4, August 2015.
[FIPS197] National Institute of Standards and Technology,
"Advanced Encryption Standard (AES)", FIPS PUB 197,
November 2001.
[SP800-38A+] National Institute of Standards and Technology,
"Recommendation for Block Cipher Modes of Operation:
Three Variants of Ciphertext Stealing for CBC Mode",
NIST Special Publication 800-38A Addendum, October 2010.
[SP800-108] National Institute of Standards and Technology,
"Recommendation for Key Derivation Using Pseudorandom
Functions", NIST Special Publication 800-108, October
2009.
10.2. Informative References
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC
4086, June 2005.
[SP800-38A] National Institute of Standards and Technology,
"Recommendation for Block Cipher Modes of Operation:
Methods and Techniques", NIST Special Publication
800-38A, December 2001.
[SP800-132] National Institute of Standards and Technology,
"Recommendation for Password-Based Key Derivation, Part
1: Storage Applications", NIST Special Publication 800-
132, June 2010.
Appendix A. Test Vectors
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Sample results for string-to-key conversion:
--------------------------------------------
Iteration count = 32768
Pass phrase = "password"
Saltp for creating 128-bit base-key:
61 65 73 31 32 38 2D 63 74 73 2D 68 6D 61 63 2D
73 68 61 32 35 36 2D 31 32 38 00 10 DF 9D D7 83
E5 BC 8A CE A1 73 0E 74 35 5F 61 41 54 48 45 4E
41 2E 4D 49 54 2E 45 44 55 72 61 65 62 75 72 6E
(The saltp is "aes128-cts-hmac-sha256-128" | 0x00 |
random 16 byte valid UTF-8 sequence | "ATHENA.MIT.EDUraeburn")
128-bit base-key:
08 9B CA 48 B1 05 EA 6E A7 7C A5 D2 F3 9D C5 E7
Saltp for creating 256-bit base-key:
61 65 73 32 35 36 2D 63 74 73 2D 68 6D 61 63 2D
73 68 61 33 38 34 2D 31 39 32 00 10 DF 9D D7 83
E5 BC 8A CE A1 73 0E 74 35 5F 61 41 54 48 45 4E
41 2E 4D 49 54 2E 45 44 55 72 61 65 62 75 72 6E
(The saltp is "aes256-cts-hmac-sha384-192" | 0x00 |
random 16 byte valid UTF-8 sequence | "ATHENA.MIT.EDUraeburn")
256-bit base-key:
45 BD 80 6D BF 6A 83 3A 9C FF C1 C9 45 89 A2 22
36 7A 79 BC 21 C4 13 71 89 06 E9 F5 78 A7 84 67
Sample results for key derivation:
----------------------------------
enctype aes128-cts-hmac-sha256-128:
128-bit base-key:
37 05 D9 60 80 C1 77 28 A0 E8 00 EA B6 E0 D2 3C
Kc value for key usage 2 (label = 0x0000000299):
B3 1A 01 8A 48 F5 47 76 F4 03 E9 A3 96 32 5D C3
Ke value for key usage 2 (label = 0x00000002AA):
9B 19 7D D1 E8 C5 60 9D 6E 67 C3 E3 7C 62 C7 2E
Ki value for key usage 2 (label = 0x0000000255):
9F DA 0E 56 AB 2D 85 E1 56 9A 68 86 96 C2 6A 6C
enctype aes256-cts-hmac-sha384-192:
256-bit base-key:
6D 40 4D 37 FA F7 9F 9D F0 D3 35 68 D3 20 66 98
00 EB 48 36 47 2E A8 A0 26 D1 6B 71 82 46 0C 52
Kc value for key usage 2 (label = 0x0000000299):
EF 57 18 BE 86 CC 84 96 3D 8B BB 50 31 E9 F5 C4
BA 41 F2 8F AF 69 E7 3D
Ke value for key usage 2 (label = 0x00000002AA):
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56 AB 22 BE E6 3D 82 D7 BC 52 27 F6 77 3F 8E A7
A5 EB 1C 82 51 60 C3 83 12 98 0C 44 2E 5C 7E 49
Ki value for key usage 2 (label = 0x0000000255):
69 B1 65 14 E3 CD 8E 56 B8 20 10 D5 C7 30 12 B6
22 C4 D0 0F FC 23 ED 1F
Sample encryptions (all using the default cipher state):
--------------------------------------------------------
These sample encryptions use the above sample key
derivation results, including use of the same
base-key and key usage values.
The following test vectors are for
enctype aes128-cts-hmac-sha256-128:
Plaintext: (empty)
Confounder:
7E 58 95 EA F2 67 24 35 BA D8 17 F5 45 A3 71 48
128-bit AES key (Ke):
9B 19 7D D1 E8 C5 60 9D 6E 67 C3 E3 7C 62 C7 2E
128-bit HMAC key (Ki):
9F DA 0E 56 AB 2D 85 E1 56 9A 68 86 96 C2 6A 6C
AES Output:
EF 85 FB 89 0B B8 47 2F 4D AB 20 39 4D CA 78 1D
Truncated HMAC Output:
AD 87 7E DA 39 D5 0C 87 0C 0D 5A 0A 8E 48 C7 18
Ciphertext (AES Output | HMAC Output):
EF 85 FB 89 0B B8 47 2F 4D AB 20 39 4D CA 78 1D
AD 87 7E DA 39 D5 0C 87 0C 0D 5A 0A 8E 48 C7 18
Plaintext: (length less than block size)
00 01 02 03 04 05
Confounder:
7B CA 28 5E 2F D4 13 0F B5 5B 1A 5C 83 BC 5B 24
128-bit AES key (Ke):
9B 19 7D D1 E8 C5 60 9D 6E 67 C3 E3 7C 62 C7 2E
128-bit HMAC key (Ki):
9F DA 0E 56 AB 2D 85 E1 56 9A 68 86 96 C2 6A 6C
AES Output:
84 D7 F3 07 54 ED 98 7B AB 0B F3 50 6B EB 09 CF
B5 54 02 CE F7 E6
Truncated HMAC Output:
87 7C E9 9E 24 7E 52 D1 6E D4 42 1D FD F8 97 6C
Ciphertext:
84 D7 F3 07 54 ED 98 7B AB 0B F3 50 6B EB 09 CF
B5 54 02 CE F7 E6 87 7C E9 9E 24 7E 52 D1 6E D4
42 1D FD F8 97 6C
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Plaintext: (length equals block size)
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
Confounder:
56 AB 21 71 3F F6 2C 0A 14 57 20 0F 6F A9 94 8F
128-bit AES key (Ke):
9B 19 7D D1 E8 C5 60 9D 6E 67 C3 E3 7C 62 C7 2E
128-bit HMAC key (Ki):
9F DA 0E 56 AB 2D 85 E1 56 9A 68 86 96 C2 6A 6C
AES Output:
35 17 D6 40 F5 0D DC 8A D3 62 87 22 B3 56 9D 2A
E0 74 93 FA 82 63 25 40 80 EA 65 C1 00 8E 8F C2
Truncated HMAC Output:
95 FB 48 52 E7 D8 3E 1E 7C 48 C3 7E EB E6 B0 D3
Ciphertext:
35 17 D6 40 F5 0D DC 8A D3 62 87 22 B3 56 9D 2A
E0 74 93 FA 82 63 25 40 80 EA 65 C1 00 8E 8F C2
95 FB 48 52 E7 D8 3E 1E 7C 48 C3 7E EB E6 B0 D3
Plaintext: (length greater than block size)
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
10 11 12 13 14
Confounder:
A7 A4 E2 9A 47 28 CE 10 66 4F B6 4E 49 AD 3F AC
128-bit AES key (Ke):
9B 19 7D D1 E8 C5 60 9D 6E 67 C3 E3 7C 62 C7 2E
128-bit HMAC key (Ki):
9F DA 0E 56 AB 2D 85 E1 56 9A 68 86 96 C2 6A 6C
AES Output:
72 0F 73 B1 8D 98 59 CD 6C CB 43 46 11 5C D3 36
C7 0F 58 ED C0 C4 43 7C 55 73 54 4C 31 C8 13 BC
E1 E6 D0 72 C1
Truncated HMAC Output:
86 B3 9A 41 3C 2F 92 CA 9B 83 34 A2 87 FF CB FC
Ciphertext:
72 0F 73 B1 8D 98 59 CD 6C CB 43 46 11 5C D3 36
C7 0F 58 ED C0 C4 43 7C 55 73 54 4C 31 C8 13 BC
E1 E6 D0 72 C1 86 B3 9A 41 3C 2F 92 CA 9B 83 34
A2 87 FF CB FC
The following test vectors are for enctype
aes256-cts-hmac-sha384-192:
Plaintext: (empty)
Confounder:
F7 64 E9 FA 15 C2 76 47 8B 2C 7D 0C 4E 5F 58 E4
256-bit AES key (Ke):
56 AB 22 BE E6 3D 82 D7 BC 52 27 F6 77 3F 8E A7
A5 EB 1C 82 51 60 C3 83 12 98 0C 44 2E 5C 7E 49
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192-bit HMAC key (Ki):
69 B1 65 14 E3 CD 8E 56 B8 20 10 D5 C7 30 12 B6
22 C4 D0 0F FC 23 ED 1F
AES Output:
41 F5 3F A5 BF E7 02 6D 91 FA F9 BE 95 91 95 A0
Truncated HMAC Output:
58 70 72 73 A9 6A 40 F0 A0 19 60 62 1A C6 12 74
8B 9B BF BE 7E B4 CE 3C
Ciphertext:
41 F5 3F A5 BF E7 02 6D 91 FA F9 BE 95 91 95 A0
58 70 72 73 A9 6A 40 F0 A0 19 60 62 1A C6 12 74
8B 9B BF BE 7E B4 CE 3C
Plaintext: (length less than block size)
00 01 02 03 04 05
Confounder:
B8 0D 32 51 C1 F6 47 14 94 25 6F FE 71 2D 0B 9A
256-bit AES key (Ke):
56 AB 22 BE E6 3D 82 D7 BC 52 27 F6 77 3F 8E A7
A5 EB 1C 82 51 60 C3 83 12 98 0C 44 2E 5C 7E 49
192-bit HMAC key (Ki):
69 B1 65 14 E3 CD 8E 56 B8 20 10 D5 C7 30 12 B6
22 C4 D0 0F FC 23 ED 1F
AES Output:
4E D7 B3 7C 2B CA C8 F7 4F 23 C1 CF 07 E6 2B C7
B7 5F B3 F6 37 B9
Truncated HMAC Output:
F5 59 C7 F6 64 F6 9E AB 7B 60 92 23 75 26 EA 0D
1F 61 CB 20 D6 9D 10 F2
Ciphertext:
4E D7 B3 7C 2B CA C8 F7 4F 23 C1 CF 07 E6 2B C7
B7 5F B3 F6 37 B9 F5 59 C7 F6 64 F6 9E AB 7B 60
92 23 75 26 EA 0D 1F 61 CB 20 D6 9D 10 F2
Plaintext: (length equals block size)
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
Confounder:
53 BF 8A 0D 10 52 65 D4 E2 76 42 86 24 CE 5E 63
256-bit AES key (Ke):
56 AB 22 BE E6 3D 82 D7 BC 52 27 F6 77 3F 8E A7
A5 EB 1C 82 51 60 C3 83 12 98 0C 44 2E 5C 7E 49
192-bit HMAC key (Ki):
69 B1 65 14 E3 CD 8E 56 B8 20 10 D5 C7 30 12 B6
22 C4 D0 0F FC 23 ED 1F
AES Output:
BC 47 FF EC 79 98 EB 91 E8 11 5C F8 D1 9D AC 4B
BB E2 E1 63 E8 7D D3 7F 49 BE CA 92 02 77 64 F6
Truncated HMAC Output:
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8C F5 1F 14 D7 98 C2 27 3F 35 DF 57 4D 1F 93 2E
40 C4 FF 25 5B 36 A2 66
Ciphertext:
BC 47 FF EC 79 98 EB 91 E8 11 5C F8 D1 9D AC 4B
BB E2 E1 63 E8 7D D3 7F 49 BE CA 92 02 77 64 F6
8C F5 1F 14 D7 98 C2 27 3F 35 DF 57 4D 1F 93 2E
40 C4 FF 25 5B 36 A2 66
Plaintext: (length greater than block size)
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
10 11 12 13 14
Confounder:
76 3E 65 36 7E 86 4F 02 F5 51 53 C7 E3 B5 8A F1
256-bit AES key (Ke):
56 AB 22 BE E6 3D 82 D7 BC 52 27 F6 77 3F 8E A7
A5 EB 1C 82 51 60 C3 83 12 98 0C 44 2E 5C 7E 49
192-bit HMAC key (Ki):
69 B1 65 14 E3 CD 8E 56 B8 20 10 D5 C7 30 12 B6
22 C4 D0 0F FC 23 ED 1F
AES Output:
40 01 3E 2D F5 8E 87 51 95 7D 28 78 BC D2 D6 FE
10 1C CF D5 56 CB 1E AE 79 DB 3C 3E E8 64 29 F2
B2 A6 02 AC 86
Truncated HMAC Output:
FE F6 EC B6 47 D6 29 5F AE 07 7A 1F EB 51 75 08
D2 C1 6B 41 92 E0 1F 62
Ciphertext:
40 01 3E 2D F5 8E 87 51 95 7D 28 78 BC D2 D6 FE
10 1C CF D5 56 CB 1E AE 79 DB 3C 3E E8 64 29 F2
B2 A6 02 AC 86 FE F6 EC B6 47 D6 29 5F AE 07 7A
1F EB 51 75 08 D2 C1 6B 41 92 E0 1F 62
Sample checksums:
-----------------
These sample checksums use the above sample key
derivation results, including use of the same
base-key and key usage values.
Checksum type: hmac-sha256-128-aes128
128-bit HMAC key (Kc):
B3 1A 01 8A 48 F5 47 76 F4 03 E9 A3 96 32 5D C3
Plaintext:
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
10 11 12 13 14
Checksum:
D7 83 67 18 66 43 D6 7B 41 1C BA 91 39 FC 1D EE
Checksum type: hmac-sha384-192-aes256
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192-bit HMAC key (Kc):
EF 57 18 BE 86 CC 84 96 3D 8B BB 50 31 E9 F5 C4
BA 41 F2 8F AF 69 E7 3D
Plaintext:
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
10 11 12 13 14
Checksum:
45 EE 79 15 67 EE FC A3 7F 4A C1 E0 22 2D E8 0D
43 C3 BF A0 66 99 67 2A
Sample pseudorandom function (PRF) invocations:
----------------------------------------
PRF input octet-string: "test" (0x74657374)
enctype aes128-cts-hmac-sha256-128:
input-key value / HMAC-SHA-256 key:
37 05 D9 60 80 C1 77 28 A0 E8 00 EA B6 E0 D2 3C
HMAC-SHA-256 input message:
00 00 00 01 70 72 66 00 74 65 73 74 00 00 01 00
PRF output:
9D 18 86 16 F6 38 52 FE 86 91 5B B8 40 B4 A8 86
FF 3E 6B B0 F8 19 B4 9B 89 33 93 D3 93 85 42 95
enctype aes256-cts-hmac-sha384-192:
input-key value / HMAC-SHA-384 key:
6D 40 4D 37 FA F7 9F 9D F0 D3 35 68 D3 20 66 98
00 EB 48 36 47 2E A8 A0 26 D1 6B 71 82 46 0C 52
HMAC-SHA-384 input message:
00 00 00 01 70 72 66 00 74 65 73 74 00 00 01 80
PRF output:
98 01 F6 9A 36 8C 2B F6 75 E5 95 21 E1 77 D9 A0
7F 67 EF E1 CF DE 8D 3C 8D 6F 6A 02 56 E3 B1 7D
B3 C1 B6 2A D1 B8 55 33 60 D1 73 67 EB 15 14 D2
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Authors' Addresses
Michael J. Jenkins
National Security Agency
EMail: mjjenki@tycho.ncsc.mil
Michael A. Peck
The MITRE Corporation
EMail: mpeck@mitre.org
Kelley W. Burgin
Email: kelley.burgin@gmail.com
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