| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 1 | /* |
| 2 | * TLS PRF (SHA1 + MD5) |
| 3 | * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi> |
| 4 | * |
| 5 | * This software may be distributed under the terms of the BSD license. |
| 6 | * See README for more details. |
| 7 | */ |
| 8 | |
| 9 | #include "includes.h" |
| 10 | |
| 11 | #include "common.h" |
| 12 | #include "sha1.h" |
| 13 | #include "md5.h" |
| 14 | |
| 15 | |
| 16 | /** |
| 17 | * tls_prf_sha1_md5 - Pseudo-Random Function for TLS (TLS-PRF, RFC 2246) |
| 18 | * @secret: Key for PRF |
| 19 | * @secret_len: Length of the key in bytes |
| 20 | * @label: A unique label for each purpose of the PRF |
| 21 | * @seed: Seed value to bind into the key |
| 22 | * @seed_len: Length of the seed |
| 23 | * @out: Buffer for the generated pseudo-random key |
| 24 | * @outlen: Number of bytes of key to generate |
| 25 | * Returns: 0 on success, -1 on failure. |
| 26 | * |
| 27 | * This function is used to derive new, cryptographically separate keys from a |
| 28 | * given key in TLS. This PRF is defined in RFC 2246, Chapter 5. |
| 29 | */ |
| 30 | int tls_prf_sha1_md5(const u8 *secret, size_t secret_len, const char *label, |
| 31 | const u8 *seed, size_t seed_len, u8 *out, size_t outlen) |
| 32 | { |
| 33 | size_t L_S1, L_S2, i; |
| 34 | const u8 *S1, *S2; |
| 35 | u8 A_MD5[MD5_MAC_LEN], A_SHA1[SHA1_MAC_LEN]; |
| 36 | u8 P_MD5[MD5_MAC_LEN], P_SHA1[SHA1_MAC_LEN]; |
| 37 | int MD5_pos, SHA1_pos; |
| 38 | const u8 *MD5_addr[3]; |
| 39 | size_t MD5_len[3]; |
| 40 | const unsigned char *SHA1_addr[3]; |
| 41 | size_t SHA1_len[3]; |
| 42 | |
| 43 | MD5_addr[0] = A_MD5; |
| 44 | MD5_len[0] = MD5_MAC_LEN; |
| 45 | MD5_addr[1] = (unsigned char *) label; |
| 46 | MD5_len[1] = os_strlen(label); |
| 47 | MD5_addr[2] = seed; |
| 48 | MD5_len[2] = seed_len; |
| 49 | |
| 50 | SHA1_addr[0] = A_SHA1; |
| 51 | SHA1_len[0] = SHA1_MAC_LEN; |
| 52 | SHA1_addr[1] = (unsigned char *) label; |
| 53 | SHA1_len[1] = os_strlen(label); |
| 54 | SHA1_addr[2] = seed; |
| 55 | SHA1_len[2] = seed_len; |
| 56 | |
| 57 | /* RFC 2246, Chapter 5 |
| 58 | * A(0) = seed, A(i) = HMAC(secret, A(i-1)) |
| 59 | * P_hash = HMAC(secret, A(1) + seed) + HMAC(secret, A(2) + seed) + .. |
| 60 | * PRF = P_MD5(S1, label + seed) XOR P_SHA-1(S2, label + seed) |
| 61 | */ |
| 62 | |
| 63 | L_S1 = L_S2 = (secret_len + 1) / 2; |
| 64 | S1 = secret; |
| 65 | S2 = secret + L_S1; |
| 66 | if (secret_len & 1) { |
| 67 | /* The last byte of S1 will be shared with S2 */ |
| 68 | S2--; |
| 69 | } |
| 70 | |
| 71 | hmac_md5_vector(S1, L_S1, 2, &MD5_addr[1], &MD5_len[1], A_MD5); |
| 72 | hmac_sha1_vector(S2, L_S2, 2, &SHA1_addr[1], &SHA1_len[1], A_SHA1); |
| 73 | |
| 74 | MD5_pos = MD5_MAC_LEN; |
| 75 | SHA1_pos = SHA1_MAC_LEN; |
| 76 | for (i = 0; i < outlen; i++) { |
| 77 | if (MD5_pos == MD5_MAC_LEN) { |
| 78 | hmac_md5_vector(S1, L_S1, 3, MD5_addr, MD5_len, P_MD5); |
| 79 | MD5_pos = 0; |
| 80 | hmac_md5(S1, L_S1, A_MD5, MD5_MAC_LEN, A_MD5); |
| 81 | } |
| 82 | if (SHA1_pos == SHA1_MAC_LEN) { |
| 83 | hmac_sha1_vector(S2, L_S2, 3, SHA1_addr, SHA1_len, |
| 84 | P_SHA1); |
| 85 | SHA1_pos = 0; |
| 86 | hmac_sha1(S2, L_S2, A_SHA1, SHA1_MAC_LEN, A_SHA1); |
| 87 | } |
| 88 | |
| 89 | out[i] = P_MD5[MD5_pos] ^ P_SHA1[SHA1_pos]; |
| 90 | |
| 91 | MD5_pos++; |
| 92 | SHA1_pos++; |
| 93 | } |
| 94 | |
| 95 | forced_memzero(A_MD5, MD5_MAC_LEN); |
| 96 | forced_memzero(P_MD5, MD5_MAC_LEN); |
| 97 | forced_memzero(A_SHA1, SHA1_MAC_LEN); |
| 98 | forced_memzero(P_SHA1, SHA1_MAC_LEN); |
| 99 | |
| 100 | return 0; |
| 101 | } |