4 files changed, 625 insertions, 0 deletions

diff --git a/twmincrypt/twrsa.c b/twmincrypt/twrsa.c
new file mode 100644
index 000000000..52d6bfbc2
--- /dev/null
+++ b/twmincrypt/twrsa.c
@@ -0,0 +1,199 @@
+/* rsa.c
+**
+** Copyright 2008, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR 
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "twrsa.h"
+#include "twsha.h"
+#include "common.h"
+
+/* a[] -= mod */
+static void subM(const RSAPublicKey *key, uint32_t *a) {
+    int64_t A = 0;
+    int i;
+    for (i = 0; i < key->len; ++i) {
+        A += (uint64_t)a[i] - key->n[i];
+        a[i] = (uint32_t)A;
+        A >>= 32;
+    }
+}
+
+/* return a[] >= mod */
+static int geM(const RSAPublicKey *key, const uint32_t *a) {
+    int i;
+    for (i = key->len; i;) {
+        --i;
+        if (a[i] < key->n[i]) return 0;
+        if (a[i] > key->n[i]) return 1;
+    }
+    return 1;  /* equal */
+}
+
+/* montgomery c[] += a * b[] / R % mod */
+static void montMulAdd(const RSAPublicKey *key,
+                       uint32_t* c,
+                       const uint32_t a,
+                       const uint32_t* b) {
+    uint64_t A = (uint64_t)a * b[0] + c[0];
+    uint32_t d0 = (uint32_t)A * key->n0inv;
+    uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
+    int i;
+
+    for (i = 1; i < key->len; ++i) {
+        A = (A >> 32) + (uint64_t)a * b[i] + c[i];
+        B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
+        c[i - 1] = (uint32_t)B;
+    }
+
+    A = (A >> 32) + (B >> 32);
+
+    c[i - 1] = (uint32_t)A;
+
+    if (A >> 32) {
+        subM(key, c);
+    }
+}
+
+/* montgomery c[] = a[] * b[] / R % mod */
+static void montMul(const RSAPublicKey *key,
+                    uint32_t* c,
+                    const uint32_t* a,
+                    const uint32_t* b) {
+    int i;
+    for (i = 0; i < key->len; ++i) {
+        c[i] = 0;
+    }
+    for (i = 0; i < key->len; ++i) {
+        montMulAdd(key, c, a[i], b);
+    }
+}
+
+/* In-place public exponentiation.
+** Input and output big-endian byte array in inout.
+*/
+static void modpow3(const RSAPublicKey *key,
+                    uint8_t* inout) {
+    uint32_t a[RSANUMWORDS];
+    uint32_t aR[RSANUMWORDS];
+    uint32_t aaR[RSANUMWORDS];
+    uint32_t *aaa = aR;  /* Re-use location. */
+    int i;
+
+    /* Convert from big endian byte array to little endian word array. */
+    for (i = 0; i < key->len; ++i) {
+        uint32_t tmp =
+            (inout[((key->len - 1 - i) * 4) + 0] << 24) |
+            (inout[((key->len - 1 - i) * 4) + 1] << 16) |
+            (inout[((key->len - 1 - i) * 4) + 2] << 8) |
+            (inout[((key->len - 1 - i) * 4) + 3] << 0);
+        a[i] = tmp;
+    }
+
+    montMul(key, aR, a, key->rr);  /* aR = a * RR / R mod M   */
+    montMul(key, aaR, aR, aR);     /* aaR = aR * aR / R mod M */
+    montMul(key, aaa, aaR, a);     /* aaa = aaR * a / R mod M */
+
+    /* Make sure aaa < mod; aaa is at most 1x mod too large. */
+    if (geM(key, aaa)) {
+        subM(key, aaa);
+    }
+
+    /* Convert to bigendian byte array */
+    for (i = key->len - 1; i >= 0; --i) {
+        uint32_t tmp = aaa[i];
+        *inout++ = tmp >> 24;
+        *inout++ = tmp >> 16;
+        *inout++ = tmp >> 8;
+        *inout++ = tmp >> 0;
+    }
+}
+
+/* Expected PKCS1.5 signature padding bytes, for a keytool RSA signature.
+** Has the 0-length optional parameter encoded in the ASN1 (as opposed to the
+** other flavor which omits the optional parameter entirely). This code does not
+** accept signatures without the optional parameter.
+*/
+static const uint8_t padding[RSANUMBYTES - SHA_DIGEST_SIZE] = {
+    0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,
+    0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,
+    0x04,0x14
+};
+
+/* Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash.
+** Returns 0 on failure, 1 on success.
+*/
+int RSA_verify(const RSAPublicKey *key,
+               const uint8_t *signature,
+               const int len,
+               const uint8_t *sha) {
+    uint8_t buf[RSANUMBYTES];
+    int i;
+
+    if (key->len != RSANUMWORDS) {
+        return 0;  /* Wrong key passed in. */
+    }
+
+    if (len != sizeof(buf)) {
+        return 0;  /* Wrong input length. */
+    }
+
+    for (i = 0; i < len; ++i) {
+        buf[i] = signature[i];
+    }
+
+    modpow3(key, buf);
+
+    /* Check pkcs1.5 padding bytes. */
+    for (i = 0; i < (int) sizeof(padding); ++i) {
+        if (buf[i] != padding[i]) {
+            return 0;
+        }
+    }
+
+    /* Check sha digest matches. */
+    for (; i < len; ++i) {
+        if (buf[i] != *sha++) {
+            return 0;
+        }
+    }
+
+    return 1;
+}
diff --git a/twmincrypt/twrsa.h b/twmincrypt/twrsa.h
new file mode 100644
index 000000000..7d7d57158
--- /dev/null
+++ b/twmincrypt/twrsa.h
@@ -0,0 +1,56 @@
+/* rsa.h
+**
+** Copyright 2008, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR 
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef _EMBEDDED_RSA_H_
+#define _EMBEDDED_RSA_H_
+
+#include <inttypes.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define RSANUMBYTES 256           /* 2048 bit key length */
+#define RSANUMWORDS (RSANUMBYTES / sizeof(uint32_t))
+
+typedef struct RSAPublicKey {
+    int len;                  /* Length of n[] in number of uint32_t */
+    uint32_t n0inv;           /* -1 / n[0] mod 2^32 */
+    uint32_t n[RSANUMWORDS];  /* modulus as little endian array */
+    uint32_t rr[RSANUMWORDS]; /* R^2 as little endian array */
+} RSAPublicKey;
+
+int RSA_verify(const RSAPublicKey *key,
+               const uint8_t* signature,
+               const int len,
+               const uint8_t* sha);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/twmincrypt/twsha.c b/twmincrypt/twsha.c
new file mode 100644
index 000000000..ac712c245
--- /dev/null
+++ b/twmincrypt/twsha.c
@@ -0,0 +1,307 @@
+/* sha.c
+**
+** Copyright 2008, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "twsha.h"
+
+// Some machines lack byteswap.h and endian.h.  These have to use the
+// slower code, even if they're little-endian.
+
+#if defined(HAVE_ENDIAN_H) && defined(HAVE_LITTLE_ENDIAN)
+
+#include <byteswap.h>
+#include <memory.h>
+
+// This version is about 28% faster than the generic version below,
+// but assumes little-endianness.
+
+static inline uint32_t ror27(uint32_t val) {
+    return (val >> 27) | (val << 5);
+}
+static inline uint32_t ror2(uint32_t val) {
+    return (val >> 2) | (val << 30);
+}
+static inline uint32_t ror31(uint32_t val) {
+    return (val >> 31) | (val << 1);
+}
+
+static void SHA1_Transform(SHA_CTX* ctx) {
+    uint32_t W[80];
+    register uint32_t A, B, C, D, E;
+    int t;
+
+    A = ctx->state[0];
+    B = ctx->state[1];
+    C = ctx->state[2];
+    D = ctx->state[3];
+    E = ctx->state[4];
+
+#define SHA_F1(A,B,C,D,E,t)                     \
+    E += ror27(A) +                             \
+        (W[t] = bswap_32(ctx->buf.w[t])) +      \
+        (D^(B&(C^D))) + 0x5A827999;             \
+    B = ror2(B);
+
+    for (t = 0; t < 15; t += 5) {
+        SHA_F1(A,B,C,D,E,t + 0);
+        SHA_F1(E,A,B,C,D,t + 1);
+        SHA_F1(D,E,A,B,C,t + 2);
+        SHA_F1(C,D,E,A,B,t + 3);
+        SHA_F1(B,C,D,E,A,t + 4);
+    }
+    SHA_F1(A,B,C,D,E,t + 0);  // 16th one, t == 15
+
+#undef SHA_F1
+
+#define SHA_F1(A,B,C,D,E,t)                                     \
+    E += ror27(A) +                                             \
+        (W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) +   \
+        (D^(B&(C^D))) + 0x5A827999;                             \
+    B = ror2(B);
+
+    SHA_F1(E,A,B,C,D,t + 1);
+    SHA_F1(D,E,A,B,C,t + 2);
+    SHA_F1(C,D,E,A,B,t + 3);
+    SHA_F1(B,C,D,E,A,t + 4);
+
+#undef SHA_F1
+
+#define SHA_F2(A,B,C,D,E,t)                                     \
+    E += ror27(A) +                                             \
+        (W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) +   \
+        (B^C^D) + 0x6ED9EBA1;                                   \
+    B = ror2(B);
+
+    for (t = 20; t < 40; t += 5) {
+        SHA_F2(A,B,C,D,E,t + 0);
+        SHA_F2(E,A,B,C,D,t + 1);
+        SHA_F2(D,E,A,B,C,t + 2);
+        SHA_F2(C,D,E,A,B,t + 3);
+        SHA_F2(B,C,D,E,A,t + 4);
+    }
+
+#undef SHA_F2
+
+#define SHA_F3(A,B,C,D,E,t)                                     \
+    E += ror27(A) +                                             \
+        (W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) +   \
+        ((B&C)|(D&(B|C))) + 0x8F1BBCDC;                         \
+    B = ror2(B);
+
+    for (; t < 60; t += 5) {
+        SHA_F3(A,B,C,D,E,t + 0);
+        SHA_F3(E,A,B,C,D,t + 1);
+        SHA_F3(D,E,A,B,C,t + 2);
+        SHA_F3(C,D,E,A,B,t + 3);
+        SHA_F3(B,C,D,E,A,t + 4);
+    }
+
+#undef SHA_F3
+
+#define SHA_F4(A,B,C,D,E,t)                                     \
+    E += ror27(A) +                                             \
+        (W[t] = ror31(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16])) +   \
+        (B^C^D) + 0xCA62C1D6;                                   \
+    B = ror2(B);
+
+    for (; t < 80; t += 5) {
+        SHA_F4(A,B,C,D,E,t + 0);
+        SHA_F4(E,A,B,C,D,t + 1);
+        SHA_F4(D,E,A,B,C,t + 2);
+        SHA_F4(C,D,E,A,B,t + 3);
+        SHA_F4(B,C,D,E,A,t + 4);
+    }
+
+#undef SHA_F4
+
+    ctx->state[0] += A;
+    ctx->state[1] += B;
+    ctx->state[2] += C;
+    ctx->state[3] += D;
+    ctx->state[4] += E;
+}
+
+void SHA_update(SHA_CTX* ctx, const void* data, int len) {
+    int i = ctx->count % sizeof(ctx->buf);
+    const uint8_t* p = (const uint8_t*)data;
+
+    ctx->count += len;
+
+    while (len > sizeof(ctx->buf) - i) {
+        memcpy(&ctx->buf.b[i], p, sizeof(ctx->buf) - i);
+        len -= sizeof(ctx->buf) - i;
+        p += sizeof(ctx->buf) - i;
+        SHA1_Transform(ctx);
+        i = 0;
+    }
+
+    while (len--) {
+        ctx->buf.b[i++] = *p++;
+        if (i == sizeof(ctx->buf)) {
+            SHA1_Transform(ctx);
+            i = 0;
+        }
+    }
+}
+
+
+const uint8_t* SHA_final(SHA_CTX* ctx) {
+    uint64_t cnt = ctx->count * 8;
+    int i;
+
+    SHA_update(ctx, (uint8_t*)"\x80", 1);
+    while ((ctx->count % sizeof(ctx->buf)) != (sizeof(ctx->buf) - 8)) {
+        SHA_update(ctx, (uint8_t*)"\0", 1);
+    }
+    for (i = 0; i < 8; ++i) {
+        uint8_t tmp = cnt >> ((7 - i) * 8);
+        SHA_update(ctx, &tmp, 1);
+    }
+
+    for (i = 0; i < 5; i++) {
+        ctx->buf.w[i] = bswap_32(ctx->state[i]);
+    }
+
+    return ctx->buf.b;
+}
+
+#else   // #if defined(HAVE_ENDIAN_H) && defined(HAVE_LITTLE_ENDIAN)
+
+#define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))
+
+static void SHA1_transform(SHA_CTX *ctx) {
+    uint32_t W[80];
+    uint32_t A, B, C, D, E;
+    uint8_t *p = ctx->buf;
+    int t;
+
+    for(t = 0; t < 16; ++t) {
+        uint32_t tmp =  *p++ << 24;
+        tmp |= *p++ << 16;
+        tmp |= *p++ << 8;
+        tmp |= *p++;
+        W[t] = tmp;
+    }
+
+    for(; t < 80; t++) {
+        W[t] = rol(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
+    }
+
+    A = ctx->state[0];
+    B = ctx->state[1];
+    C = ctx->state[2];
+    D = ctx->state[3];
+    E = ctx->state[4];
+
+    for(t = 0; t < 80; t++) {
+        uint32_t tmp = rol(5,A) + E + W[t];
+
+        if (t < 20)
+            tmp += (D^(B&(C^D))) + 0x5A827999;
+        else if ( t < 40)
+            tmp += (B^C^D) + 0x6ED9EBA1;
+        else if ( t < 60)
+            tmp += ((B&C)|(D&(B|C))) + 0x8F1BBCDC;
+        else
+            tmp += (B^C^D) + 0xCA62C1D6;
+
+        E = D;
+        D = C;
+        C = rol(30,B);
+        B = A;
+        A = tmp;
+    }
+
+    ctx->state[0] += A;
+    ctx->state[1] += B;
+    ctx->state[2] += C;
+    ctx->state[3] += D;
+    ctx->state[4] += E;
+}
+
+void SHA_update(SHA_CTX *ctx, const void *data, int len) {
+    int i = ctx->count % sizeof(ctx->buf);
+    const uint8_t* p = (const uint8_t*)data;
+
+    ctx->count += len;
+
+    while (len--) {
+        ctx->buf[i++] = *p++;
+        if (i == sizeof(ctx->buf)) {
+            SHA1_transform(ctx);
+            i = 0;
+        }
+    }
+}
+const uint8_t *SHA_final(SHA_CTX *ctx) {
+    uint8_t *p = ctx->buf;
+    uint64_t cnt = ctx->count * 8;
+    int i;
+
+    SHA_update(ctx, (uint8_t*)"\x80", 1);
+    while ((ctx->count % sizeof(ctx->buf)) != (sizeof(ctx->buf) - 8)) {
+        SHA_update(ctx, (uint8_t*)"\0", 1);
+    }
+    for (i = 0; i < 8; ++i) {
+        uint8_t tmp = cnt >> ((7 - i) * 8);
+        SHA_update(ctx, &tmp, 1);
+    }
+
+    for (i = 0; i < 5; i++) {
+        uint32_t tmp = ctx->state[i];
+        *p++ = tmp >> 24;
+        *p++ = tmp >> 16;
+        *p++ = tmp >> 8;
+        *p++ = tmp >> 0;
+    }
+
+    return ctx->buf;
+}
+
+#endif // endianness
+
+void SHA_init(SHA_CTX* ctx) {
+    ctx->state[0] = 0x67452301;
+    ctx->state[1] = 0xEFCDAB89;
+    ctx->state[2] = 0x98BADCFE;
+    ctx->state[3] = 0x10325476;
+    ctx->state[4] = 0xC3D2E1F0;
+    ctx->count = 0;
+}
+
+/* Convenience function */
+const uint8_t* SHA(const void *data, int len, uint8_t *digest) {
+    const uint8_t *p;
+    int i;
+    SHA_CTX ctx;
+    SHA_init(&ctx);
+    SHA_update(&ctx, data, len);
+    p = SHA_final(&ctx);
+    for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+        digest[i] = *p++;
+    }
+    return digest;
+}
diff --git a/twmincrypt/twsha.h b/twmincrypt/twsha.h
new file mode 100644
index 000000000..af63e8775
--- /dev/null
+++ b/twmincrypt/twsha.h
@@ -0,0 +1,63 @@
+/* sha.h
+**
+** Copyright 2008, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef _EMBEDDED_SHA_H_
+#define _EMBEDDED_SHA_H_
+
+#include <inttypes.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct SHA_CTX {
+    uint64_t count;
+    uint32_t state[5];
+#if defined(HAVE_ENDIAN_H) && defined(HAVE_LITTLE_ENDIAN)
+    union {
+        uint8_t b[64];
+        uint32_t w[16];
+    } buf;
+#else
+    uint8_t buf[64];
+#endif
+} SHA_CTX;
+
+void SHA_init(SHA_CTX* ctx);
+void SHA_update(SHA_CTX* ctx, const void* data, int len);
+const uint8_t* SHA_final(SHA_CTX* ctx);
+
+/* Convenience method. Returns digest parameter value. */
+const uint8_t* SHA(const void* data, int len, uint8_t* digest);
+
+#define SHA_DIGEST_SIZE 20
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif