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cipher
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add tea cbc c

This commit is contained in:
Wang Yaofu 2021-08-18 22:24:34 +08:00 committed by GitHub
parent 7083dd903c
commit ee849de64c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 165 additions and 0 deletions
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cipher/tea.c Normal file
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#include <stdint.h>
#include "tea.h"
uint32_t UnpackUint32(
unsigned char *b
) {
return (uint32_t) b[0] | (uint32_t) b[1] << 8 | (uint32_t) b[2] << 16 | (uint32_t) b[3] << 24;
}
void PackUint32(
unsigned char *dst,
uint32_t n
) {
dst[0] = n;
dst[1] = n >> 8;
dst[2] = n >> 16;
dst[3] = n >> 24;
return;
}
void EncryptBlock(
uint32_t *v,
uint32_t *k
) {
uint32_t delta = 0x9e3779b9, sum = 0, i;
i = 0;
do {
sum += delta;
v[0] += ((v[1] << 4) + k[0]) ^ (v[1] + sum) ^ ((v[1] >> 5) + k[1]);
v[1] += ((v[0] << 4) + k[2]) ^ (v[0] + sum) ^ ((v[0] >> 5) + k[3]);
i++;
} while (i < 32);
}
void TeaEncryptCBC(
unsigned char *crypted_text,
unsigned char *plain_text,
int len,
unsigned char iv[8],
unsigned char key[16]
) {
unsigned char *src = plain_text;
unsigned char *dst = crypted_text;
unsigned char padded[8];
uint32_t v[2], k[4];
int i;
v[0] = UnpackUint32(&iv[0]);
v[1] = UnpackUint32(&iv[4]);
k[0] = UnpackUint32(&key[0]);
k[1] = UnpackUint32(&key[4]);
k[2] = UnpackUint32(&key[8]);
k[3] = UnpackUint32(&key[12]);
do {
v[0] ^= UnpackUint32(&src[0]);
v[1] ^= UnpackUint32(&src[4]);
EncryptBlock(v, k);
PackUint32(&dst[0], v[0]);
PackUint32(&dst[4], v[1]);
src += 8;
dst += 8;
len -= 8;
} while (len >= 8);
i = 0;
do {
padded[i] = src[i];
i++;
} while (i < len);
i = len;
do {
padded[i] = 8 - len;
i++;
} while (i < 8);
v[0] ^= UnpackUint32(&padded[0]);
v[1] ^= UnpackUint32(&padded[4]);
EncryptBlock(v, k);
PackUint32(&dst[0], v[0]);
PackUint32(&dst[4], v[1]);
}
void DecryptBlock(
uint32_t *v,
uint32_t *k
) {
uint32_t delta = 0x9e3779b9, sum = 0xc6ef3720, i;
i = 0;
do {
v[1] -= ((v[0] << 4) + k[2]) ^ (v[0] + sum) ^ ((v[0] >> 5) + k[3]);
v[0] -= ((v[1] << 4) + k[0]) ^ (v[1] + sum) ^ ((v[1] >> 5) + k[1]);
sum -= delta;
i++;
} while (i < 32);
}
int TeaDecryptCBC(
unsigned char *crypted_text,
unsigned char *plain_text,
int len,
unsigned char iv[8],
unsigned char key[16]
) {
unsigned char *dst = crypted_text;
unsigned char *src = plain_text;
unsigned char padded[8];
uint32_t v[2], prev[2], tmp[2], k[4];
int i;
prev[0] = UnpackUint32(&iv[0]);
prev[1] = UnpackUint32(&iv[4]);
k[0] = UnpackUint32(&key[0]);
k[1] = UnpackUint32(&key[4]);
k[2] = UnpackUint32(&key[8]);
k[3] = UnpackUint32(&key[12]);
do {
v[0] = tmp[0] = UnpackUint32(&src[0]);
v[1] = tmp[1] = UnpackUint32(&src[4]);
DecryptBlock(v, k);
PackUint32(&dst[0], v[0] ^ prev[0]);
PackUint32(&dst[4], v[1] ^ prev[1]);
prev[0] = tmp[0];
prev[1] = tmp[1];
src += 8;
dst += 8;
len -= 8;
} while (len > 8);
if (len == 8) {
v[0] = UnpackUint32(&src[0]);
v[1] = UnpackUint32(&src[4]);
DecryptBlock(v, k);
PackUint32(&padded[0], v[0] ^ prev[0]);
PackUint32(&padded[4], v[1] ^ prev[1]);
} else {
return -1;
}
if (padded[7] <= 8) {
i = 0;
} else {
return -1;
}
do {
dst[i] = padded[i];
i++;
} while (i < 8 - padded[7]);
return 0;
}