diff options
Diffstat (limited to 'src/lib/crypto/dk/dk_encrypt.c')
| -rw-r--r-- | src/lib/crypto/dk/dk_encrypt.c | 194 |
1 files changed, 193 insertions, 1 deletions
diff --git a/src/lib/crypto/dk/dk_encrypt.c b/src/lib/crypto/dk/dk_encrypt.c index eb9fe5f..6016b1d 100644 --- a/src/lib/crypto/dk/dk_encrypt.c +++ b/src/lib/crypto/dk/dk_encrypt.c @@ -108,7 +108,7 @@ krb5_dk_encrypt(enc, hash, key, usage, ivec, input, output) d1.data[2] = (usage>>8)&0xff; d1.data[3] = usage&0xff; - d1.data[4] = 0xAA; + d1.data[4] = (char) 0xAA; if ((ret = krb5_derive_key(enc, key, &ke, &d1))) goto cleanup; @@ -177,6 +177,198 @@ cleanup: return(ret); } +/* Not necessarily "AES", per se, but "a CBC+CTS mode block cipher + with a 96-bit truncated HMAC". */ +void +krb5int_aes_encrypt_length(enc, hash, inputlen, length) + const struct krb5_enc_provider *enc; + const struct krb5_hash_provider *hash; + size_t inputlen; + size_t *length; +{ + size_t blocksize, hashsize; + + (*(enc->block_size))(&blocksize); + hashsize = 96 / 8; + + /* No roundup, since CTS requires no padding once we've hit the + block size. */ + *length = blocksize+inputlen + hashsize; +} + +static krb5_error_code +trunc_hmac (const struct krb5_hash_provider *hash, + const krb5_keyblock *ki, int num, + const krb5_data *input, const krb5_data *output) +{ + size_t hashsize; + krb5_data tmp; + krb5_error_code ret; + + (hash->hash_size)(&hashsize); + if (hashsize < output->length) + return KRB5_CRYPTO_INTERNAL; + tmp.length = hashsize; + tmp.data = malloc(hashsize); + if (tmp.data == NULL) + return errno; + ret = krb5_hmac(hash, ki, num, input, &tmp); + if (ret == 0) + memcpy(output->data, tmp.data, output->length); + memset(tmp.data, 0, hashsize); + free(tmp.data); + return ret; +} + +krb5_error_code +krb5int_aes_dk_encrypt(enc, hash, key, usage, ivec, input, output) + const struct krb5_enc_provider *enc; + const struct krb5_hash_provider *hash; + const krb5_keyblock *key; + krb5_keyusage usage; + const krb5_data *ivec; + const krb5_data *input; + krb5_data *output; +{ + size_t blocksize, keybytes, keylength, plainlen, enclen; + krb5_error_code ret; + unsigned char constantdata[K5CLENGTH]; + krb5_data d1, d2; + unsigned char *plaintext, *kedata, *kidata, *cn; + krb5_keyblock ke, ki; + + /* allocate and set up plaintext and to-be-derived keys */ + + (*(enc->block_size))(&blocksize); + (*(enc->keysize))(&keybytes, &keylength); + plainlen = blocksize+input->length; + + krb5int_aes_encrypt_length(enc, hash, input->length, &enclen); + + /* key->length, ivec will be tested in enc->encrypt */ + + if (output->length < enclen) + return(KRB5_BAD_MSIZE); + + if ((kedata = (unsigned char *) malloc(keylength)) == NULL) + return(ENOMEM); + if ((kidata = (unsigned char *) malloc(keylength)) == NULL) { + free(kedata); + return(ENOMEM); + } + if ((plaintext = (unsigned char *) malloc(plainlen)) == NULL) { + free(kidata); + free(kedata); + return(ENOMEM); + } + + ke.contents = kedata; + ke.length = keylength; + ki.contents = kidata; + ki.length = keylength; + + /* derive the keys */ + + d1.data = constantdata; + d1.length = K5CLENGTH; + + d1.data[0] = (usage>>24)&0xff; + d1.data[1] = (usage>>16)&0xff; + d1.data[2] = (usage>>8)&0xff; + d1.data[3] = usage&0xff; + + d1.data[4] = (char) 0xAA; + + if ((ret = krb5_derive_key(enc, key, &ke, &d1))) + goto cleanup; + + d1.data[4] = 0x55; + + if ((ret = krb5_derive_key(enc, key, &ki, &d1))) + goto cleanup; + + /* put together the plaintext */ + + d1.length = blocksize; + d1.data = plaintext; + + if ((ret = krb5_c_random_make_octets(/* XXX */ 0, &d1))) + goto cleanup; + + memcpy(plaintext+blocksize, input->data, input->length); + + /* Ciphertext stealing; there should be no more. */ + if (plainlen != blocksize + input->length) + abort(); + + /* encrypt the plaintext */ + + d1.length = plainlen; + d1.data = plaintext; + + d2.length = plainlen; + d2.data = output->data; + + if ((ret = ((*(enc->encrypt))(&ke, ivec, &d1, &d2)))) + goto cleanup; + + if (ivec != NULL && ivec->length == blocksize) { + int nblocks = (d2.length + blocksize - 1) / blocksize; + cn = d2.data + blocksize * (nblocks - 2); + } else + cn = NULL; + + /* hash the plaintext */ + + d2.length = enclen - plainlen; + d2.data = output->data+plainlen; + if (d2.length != 96 / 8) + abort(); + + if ((ret = trunc_hmac(hash, &ki, 1, &d1, &d2))) { + memset(d2.data, 0, d2.length); + goto cleanup; + } + + output->length = enclen; + + /* update ivec */ + if (cn != NULL) { + memcpy(ivec->data, cn, blocksize); +#if 0 + { + int i; + printf("\n%s: output:", __func__); + for (i = 0; i < output->length; i++) { + if (i % 16 == 0) + printf("\n%s: ", __func__); + printf(" %02x", i[(unsigned char *)output->data]); + } + printf("\n%s: outputIV:", __func__); + for (i = 0; i < ivec->length; i++) { + if (i % 16 == 0) + printf("\n%s: ", __func__); + printf(" %02x", i[(unsigned char *)ivec->data]); + } + printf("\n"); fflush(stdout); + } +#endif + } + + /* ret is set correctly by the prior call */ + +cleanup: + memset(kedata, 0, keylength); + memset(kidata, 0, keylength); + memset(plaintext, 0, plainlen); + + free(plaintext); + free(kidata); + free(kedata); + + return(ret); +} + #ifdef ATHENA_DES3_KLUDGE void krb5_marc_dk_encrypt_length(enc, hash, inputlen, length) |