AhamedFayaz
commented
1 year ago ========================================================== typedef struct gcm_ctx_256b { ubyte4 table[16][4]; ubyte4 tag4[4]; ubyte4 s[4]; sbyte4 hashBufferIndex; ubyte hashBuffer[AES_BLOCK_SIZE]; ubyte4 alen; ubyte4 dlen; AES_CTR_Ctx ctx; } gcm_ctx_256b;
typedef struct aesCTRCipherContext { aesCipherContext ctx; union { ubyte counterBlock[AES_BLOCK_SIZE]; / counter block / ubyte4 ctr[4]; } u; ubyte encBlock[AES_BLOCK_SIZE]; / encrypted counter block / ubyte offset; / offset of unused byte in the encBlock / } aesCTRCipherContext, AES_CTR_Ctx;
=========================================================== typedef struct {
gf_t256_a gf_t256; /* table 256*/
gcm_buf_t ctr_val; /* CTR counter value */
gcm_buf_t enc_ctr; /* encrypted CTR block */
gcm_buf_t hdr_ghv; /* ghash buffer (header) */
gcm_buf_t txt_ghv; /* ghash buffer (ciphertext) */
gf_t ghash_h; /* ghash H value */
aes_encrypt_ctx aes[1]; /* AES encryption context */
uint_32t y0_val; /* initial counter value */
uint_32t hdr_cnt; /* header bytes so far */
uint_32t txt_ccnt; /* text bytes so far (encrypt) */
uint_32t txt_acnt; /* text bytes so far (auth) */} gcm_ctx;
https://github.com/BrianGladman/modes/blob/master/gcm.h
https://security.stackexchange.com/questions/100449/what-difference-between-aes-128-gcm-and-aes-128-and-aes-128-cbc-ciphers https://www.ietf.org/rfc/rfc5246.txt
Hi,
I am working on ssl client (Mocana ssl )because of some server update I was enabling the cipher TLS_DHE_RSA_WITH_AES_128_GCM_SHA256. While handshake with server I was facing bad record mac Alert message from the server.
I was verified the time stamp and encryption status that are correct. That doesn't make any problem. I have no idea how to debug kindly give me the support how to debug.
I have got the gcm code from https://github.com/BrianGladman/modes/blob/master/gcm.h
STATUS gcm_cipher_256b(BulkCtx ctx, ubyte nonce, ubyte4 nlen, ubyte adata, ubyte4 alen, ubyte* data, ubyte4 dlen, ubyte4 verifyLen, sbyte4 encrypt) {
gcm_ctx ptr_gcm_ctx = (gcm_ctx )ctx; char tag[2][16]={0};
return (STATUS)gcm_encrypt_message(nonce, nlen, adata, alen, data, dlen, tag[0], verifyLen, ptr_gcm_ctx); }
Regards, AhamedFayaz M