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refactor solution

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This commit is contained in:
Jacob Barthelmeh
2020-01-15 09:29:10 -07:00
parent 99d657af4f
commit bd44091111
1 changed files with 15 additions and 17 deletions
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34
wolfcrypt/src/chacha.c
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@ -265,10 +265,8 @@ static void wc_Chacha_encrypt_bytes(ChaCha* ctx, const byte* m, byte* c,
word32 temp[CHACHA_CHUNK_WORDS]; /* used to make sure aligned */
word32 i;
output = (byte*)temp;
/* handle left overs */
if (ctx->left > 0) {
if (bytes > 0 && ctx->left > 0) {
wc_Chacha_wordtobyte(temp, ctx->X); /* recreate the stream */
output = (byte*)temp + CHACHA_CHUNK_BYTES - ctx->left;
for (i = 0; i < bytes && i < ctx->left; i++) {
@ -283,23 +281,11 @@ static void wc_Chacha_encrypt_bytes(ChaCha* ctx, const byte* m, byte* c,
bytes = bytes - i;
c += i;
m += i;
}
output = (byte*)temp;
}
for (; bytes > 0;) {
while (bytes >= CHACHA_CHUNK_BYTES) {
wc_Chacha_wordtobyte(temp, ctx->X);
if (bytes <= CHACHA_CHUNK_BYTES) {
for (i = 0; i < bytes; ++i) {
c[i] = m[i] ^ output[i];
}
ctx->left = CHACHA_CHUNK_BYTES - i;
/* increment the counter if no more bytes are left */
if (ctx->left == 0) {
ctx->X[CHACHA_IV_BYTES] = PLUSONE(ctx->X[CHACHA_IV_BYTES]);
}
return;
}
ctx->X[CHACHA_IV_BYTES] = PLUSONE(ctx->X[CHACHA_IV_BYTES]);
for (i = 0; i < CHACHA_CHUNK_BYTES; ++i) {
c[i] = m[i] ^ output[i];
@ -308,7 +294,19 @@ static void wc_Chacha_encrypt_bytes(ChaCha* ctx, const byte* m, byte* c,
c += CHACHA_CHUNK_BYTES;
m += CHACHA_CHUNK_BYTES;
}
if (bytes) {
/* in this case there will always be some left over since bytes is less
* than CHACHA_CHUNK_BYTES, so do not increment counter after getting
* stream in order for the stream to be recreated on next call */
wc_Chacha_wordtobyte(temp, ctx->X);
for (i = 0; i < bytes; ++i) {
c[i] = m[i] ^ output[i];
}
ctx->left = CHACHA_CHUNK_BYTES - i;
}
}
/**
* API to encrypt/decrypt a message of any size.