`nx_hmac_sha1.nx` source

↩ module page · 109 lines · 3391 B
1// hmac_sha1.nx -- HMAC with SHA-1 (RFC 2104 + FIPS 198-1).
2//
3// license_tier: INDEPENDENT_REDERIVE
4// genealogy_id: international-research-sources/nist/fips_198_1
5//
6// Interop-only primitive, like sha1.nx itself.  HMAC does not
7// rely on its inner hash's collision resistance (only pseudo-
8// randomness of the keyed mix), so HMAC-SHA1 remains safe for
9// authentication even though plain SHA-1 is broken for signatures.
10//
11// Still widely used:
12//   - TOTP / HOTP (RFC 4226 / 6238 default)
13//   - OAuth 1.0 HMAC-SHA1 signatures
14//   - AWS SigV2 / legacy API auth
15//   - PBKDF2-HMAC-SHA1 (WPA2, older WebCrypto key derivation)
16//   - Older JWT HS1 tokens
17//
18// Algorithm (RFC 2104):
19//   block_size = 64 bytes for SHA-1
20//   if len(key) > block_size: key = SHA1(key)
21//   key = key || zeros to block_size
22//   ipad = key XOR 0x36 repeated
23//   opad = key XOR 0x5C repeated
24//   tag = SHA1(opad || SHA1(ipad || msg))
25//
26// Composes sha1.nx.  Output is 20 bytes.
27//
28// Invariants:
29//   HS1  Output = 20 bytes always (HMAC-SHA1 tag length).
30//   HS2  Matches RFC 2202 test vectors (not checked in smoke,
31//        but the algorithm is textbook).
32
33// nx_safety_envelope:
34//   intended_use:       AUTO_APPLIED -- primitive-specific tuning queued
35//   sil_target:         SIL1
36//   evidence:           [bulk_applied_2026-05-16, see-file-comment-for-detail]
37//   verdict:            NOT_YET_EVALUATED
38
39import "nx_syscalls.nx"
40import "nx_sha1.nx"
41
42const HMAC_SHA1_BLOCK: i64 = 64
43const HMAC_SHA1_OUT:   i64 = 20
44
45func hmac_sha1(key: *u8, key_len: i64,
46               msg: *u8, msg_len: i64,
47               out: *u8) -> i64 {
48    let k_prime: *u8 = sys_mmap(HMAC_SHA1_BLOCK + 16)
49    var i: i64 = 0
50    while i < HMAC_SHA1_BLOCK { k_prime[i] = 0; i = i + 1 }
51
52    if key_len > HMAC_SHA1_BLOCK {
53        // Shorten long keys by hashing.
54        sha1(key, key_len, k_prime)
55    } else {
56        i = 0
57        while i < key_len {
58            k_prime[i] = key[i]
59            i = i + 1
60        }
61    }
62
63    // Inner hash: SHA1(ipad || msg).
64    let inner_buf_len: i64 = HMAC_SHA1_BLOCK + msg_len
65    let inner_buf: *u8 = sys_mmap(inner_buf_len + 16)
66    i = 0
67    while i < HMAC_SHA1_BLOCK {
68        inner_buf[i] = k_prime[i] ^ 0x36
69        i = i + 1
70    }
71    i = 0
72    while i < msg_len {
73        inner_buf[HMAC_SHA1_BLOCK + i] = msg[i]
74        i = i + 1
75    }
76    let inner_hash: *u8 = sys_mmap(32)
77    sha1(inner_buf, inner_buf_len, inner_hash)
78
79    // Outer hash: SHA1(opad || inner_hash).
80    let outer_buf_len: i64 = HMAC_SHA1_BLOCK + HMAC_SHA1_OUT
81    let outer_buf: *u8 = sys_mmap(outer_buf_len + 16)
82    i = 0
83    while i < HMAC_SHA1_BLOCK {
84        outer_buf[i] = k_prime[i] ^ 0x5C
85        i = i + 1
86    }
87    i = 0
88    while i < HMAC_SHA1_OUT {
89        outer_buf[HMAC_SHA1_BLOCK + i] = inner_hash[i]
90        i = i + 1
91    }
92    sha1(outer_buf, outer_buf_len, out)
93    return 0
94}
95
96// Compile-only smoke.
97func main() -> i64 {
98    let out: *u8 = sys_mmap(32)
99    hmac_sha1("key", 3, "The quick brown fox jumps over the lazy dog", 43, out)
100    // RFC 2202 test vector:
101    // HMAC-SHA1(key=\"key\", msg=\"The quick brown fox jumps over the lazy dog\")
102    // = de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9
103    if out[0] != 0xDE { return 1 }
104    if out[1] != 0x7C { return 2 }
105    if out[2] != 0x9B { return 3 }
106    if out[3] != 0x85 { return 4 }
107    if out[19] != 0xD9 { return 5 }
108    return 0
109}
nx_hmac_sha1.nx source

`nx_hmac_sha1.nx` source
