text: /*
   * WPA Supplicant / Crypto wrapper for internal crypto implementation
   * Copyright (c) 2006-2007, Jouni Malinen <j@w1.fi>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * Alternatively, this software may be distributed under the terms of BSD
   * license.
   *
   * See README and COPYING for more details.
   */
  
  #include "includes.h"
  
  #include "common.h"
  #include "crypto.h"
  #include "md5.h"
  #include "sha1.h"
  #include "rc4.h"
  #include "aes.h"
  #include "tls/rsa.h"
  #include "tls/bignum.h"
  #include "tls/asn1.h"
  
  
  #ifdef CONFIG_CRYPTO_INTERNAL
  
  #ifdef CONFIG_TLS_INTERNAL
  
  /* from des.c */
  struct des3_key_s {
  	u32 ek[3][32];
  	u32 dk[3][32];
  };
  
  void des3_key_setup(const u8 *key, struct des3_key_s *dkey);
  void des3_encrypt(const u8 *plain, const struct des3_key_s *key, u8 *crypt);
  void des3_decrypt(const u8 *crypt, const struct des3_key_s *key, u8 *plain);
  
  
  struct MD5Context {
  	u32 buf[4];
  	u32 bits[2];
  	u8 in[64];
  };
  
  struct SHA1Context {
  	u32 state[5];
  	u32 count[2];
  	unsigned char buffer[64];
  };
  
  
  struct crypto_hash {
  	enum crypto_hash_alg alg;
  	union {
  		struct MD5Context md5;
  		struct SHA1Context sha1;
  	} u;
  	u8 key[64];
  	size_t key_len;
  };
  
  
  struct crypto_hash * crypto_hash_init(enum crypto_hash_alg alg, const u8 *key,
  				      size_t key_len)
  {
  	struct crypto_hash *ctx;
  	u8 k_pad[64];
  	u8 tk[20];
  	size_t i;
  
  	ctx = os_zalloc(sizeof(*ctx));
  	if (ctx == NULL)
  		return NULL;
  
  	ctx->alg = alg;
  
  	switch (alg) {
  	case CRYPTO_HASH_ALG_MD5:
  		MD5Init(&ctx->u.md5);
  		break;
  	case CRYPTO_HASH_ALG_SHA1:
  		SHA1Init(&ctx->u.sha1);
  		break;
  	case CRYPTO_HASH_ALG_HMAC_MD5:
  		if (key_len > sizeof(k_pad)) {
  			MD5Init(&ctx->u.md5);
  			MD5Update(&ctx->u.md5, key, key_len);
  			MD5Final(tk, &ctx->u.md5);
  			key = tk;
  			key_len = 16;
  		}
  		os_memcpy(ctx->key, key, key_len);
  		ctx->key_len = key_len;
  
  		os_memcpy(k_pad, key, key_len);
  		os_memset(k_pad + key_len, 0, sizeof(k_pad) - key_len);
  		for (i = 0; i < sizeof(k_pad); i++)
  			k_pad[i] ^= 0x36;
  		MD5Init(&ctx->u.md5);
  		MD5Update(&ctx->u.md5, k_pad, sizeof(k_pad));
  		break;
  	case CRYPTO_HASH_ALG_HMAC_SHA1:
  		if (key_len > sizeof(k_pad)) {
  			SHA1Init(&ctx->u.sha1);
  			SHA1Update(&ctx->u.sha1, key, key_len);
  			SHA1Final(tk, &ctx->u.sha1);
  			key = tk;
  			key_len = 20;
  		}
  		os_memcpy(ctx->key, key, key_len);
  		ctx->key_len = key_len;
  
  		os_memcpy(k_pad, key, key_len);
  		os_memset(k_pad + key_len, 0, sizeof(k_pad) - key_len);
  		for (i = 0; i < sizeof(k_pad); i++)
  			k_pad[i] ^= 0x36;
  		SHA1Init(&ctx->u.sha1);
  		SHA1Update(&ctx->u.sha1, k_pad, sizeof(k_pad));
  		break;
  	default:
  		os_free(ctx);
  		return NULL;
  	}
  
  	return ctx;
  }
  
  
  void crypto_hash_update(struct crypto_hash *ctx, const u8 *data, size_t len)
  {
  	if (ctx == NULL)
  		return;
  
  	switch (ctx->alg) {
  	case CRYPTO_HASH_ALG_MD5:
  	case CRYPTO_HASH_ALG_HMAC_MD5:
  		MD5Update(&ctx->u.md5, data, len);
  		break;
  	case CRYPTO_HASH_ALG_SHA1:
  	case CRYPTO_HASH_ALG_HMAC_SHA1:
  		SHA1Update(&ctx->u.sha1, data, len);
  		break;
  	}
  }
  
  
  int crypto_hash_finish(struct crypto_hash *ctx, u8 *mac, size_t *len)
  {
  	u8 k_pad[64];
  	size_t i;
  
  	if (ctx == NULL)
  		return -2;
  
  	if (mac == NULL || len == NULL) {
  		os_free(ctx);
  		return 0;
  	}
  
  	switch (ctx->alg) {
  	case CRYPTO_HASH_ALG_MD5:
  		if (*len < 16) {
  			*len = 16;
  			os_free(ctx);
  			return -1;
  		}
  		*len = 16;
  		MD5Final(mac, &ctx->u.md5);
  		break;
  	case CRYPTO_HASH_ALG_SHA1:
  		if (*len < 20) {
  			*len = 20;
  			os_free(ctx);
  			return -1;
  		}
  		*len = 20;
  		SHA1Final(mac, &ctx->u.sha1);
  		break;
  	case CRYPTO_HASH_ALG_HMAC_MD5:
  		if (*len < 16) {
  			*len = 16;
  			os_free(ctx);
  			return -1;
  		}
  		*len = 16;
  
  		MD5Final(mac, &ctx->u.md5);
  
  		os_memcpy(k_pad, ctx->key, ctx->key_len);
  		os_memset(k_pad + ctx->key_len, 0,
  			  sizeof(k_pad) - ctx->key_len);
  		for (i = 0; i < sizeof(k_pad); i++)
  			k_pad[i] ^= 0x5c;
  		MD5Init(&ctx->u.md5);
  		MD5Update(&ctx->u.md5, k_pad, sizeof(k_pad));
  		MD5Update(&ctx->u.md5, mac, 16);
  		MD5Final(mac, &ctx->u.md5);
  		break;
  	case CRYPTO_HASH_ALG_HMAC_SHA1:
  		if (*len < 20) {
  			*len = 20;
  			os_free(ctx);
  			return -1;
  		}
  		*len = 20;
  
  		SHA1Final(mac, &ctx->u.sha1);
  
  		os_memcpy(k_pad, ctx->key, ctx->key_len);
  		os_memset(k_pad + ctx->key_len, 0,
  			  sizeof(k_pad) - ctx->key_len);
  		for (i = 0; i < sizeof(k_pad); i++)
  			k_pad[i] ^= 0x5c;
  		SHA1Init(&ctx->u.sha1);
  		SHA1Update(&ctx->u.sha1, k_pad, sizeof(k_pad));
  		SHA1Update(&ctx->u.sha1, mac, 20);
  		SHA1Final(mac, &ctx->u.sha1);
  		break;
  	}
  
  	os_free(ctx);
  
  	return 0;
  }
  
  
  struct crypto_cipher {
  	enum crypto_cipher_alg alg;
  	union {
  		struct {
  			size_t used_bytes;
  			u8 key[16];
  			size_t keylen;
  		} rc4;
  		struct {
  			u8 cbc[32];
  			size_t block_size;
  			void *ctx_enc;
  			void *ctx_dec;
  		} aes;
  		struct {
  			struct des3_key_s key;
  			u8 cbc[8];
  		} des3;
  	} u;
  };
  
  
  struct crypto_cipher * crypto_cipher_init(enum crypto_cipher_alg alg,
  					  const u8 *iv, const u8 *key,
  					  size_t key_len)
  {
  	struct crypto_cipher *ctx;
  
  	ctx = os_zalloc(sizeof(*ctx));
  	if (ctx == NULL)
  		return NULL;
  
  	ctx->alg = alg;
  
  	switch (alg) {
  	case CRYPTO_CIPHER_ALG_RC4:
  		if (key_len > sizeof(ctx->u.rc4.key)) {
  			os_free(ctx);
  			return NULL;
  		}
  		ctx->u.rc4.keylen = key_len;
  		os_memcpy(ctx->u.rc4.key, key, key_len);
  		break;
  	case CRYPTO_CIPHER_ALG_AES:
  		if (key_len > sizeof(ctx->u.aes.cbc)) {
  			os_free(ctx);
  			return NULL;
  		}
  		ctx->u.aes.ctx_enc = aes_encrypt_init(key, key_len);
  		if (ctx->u.aes.ctx_enc == NULL) {
  			os_free(ctx);
  			return NULL;
  		}
  		ctx->u.aes.ctx_dec = aes_decrypt_init(key, key_len);
  		if (ctx->u.aes.ctx_dec == NULL) {
  			aes_encrypt_deinit(ctx->u.aes.ctx_enc);
  			os_free(ctx);
  			return NULL;
  		}
  		ctx->u.aes.block_size = key_len;
  		os_memcpy(ctx->u.aes.cbc, iv, ctx->u.aes.block_size);
  		break;
  	case CRYPTO_CIPHER_ALG_3DES:
  		if (key_len != 24) {
  			os_free(ctx);
  			return NULL;
  		}
  		des3_key_setup(key, &ctx->u.des3.key);
  		os_memcpy(ctx->u.des3.cbc, iv, 8);
  		break;
  	default:
  		os_free(ctx);
  		return NULL;
  	}
  
  	return ctx;
  }
  
  
  int crypto_cipher_encrypt(struct crypto_cipher *ctx, const u8 *plain,
  			  u8 *crypt, size_t len)
  {
  	size_t i, j, blocks;
  
  	switch (ctx->alg) {
  	case CRYPTO_CIPHER_ALG_RC4:
  		if (plain != crypt)
  			os_memcpy(crypt, plain, len);
  		rc4_skip(ctx->u.rc4.key, ctx->u.rc4.keylen,
  			 ctx->u.rc4.used_bytes, crypt, len);
  		ctx->u.rc4.used_bytes += len;
  		break;
  	case CRYPTO_CIPHER_ALG_AES:
  		if (len % ctx->u.aes.block_size)
  			return -1;
  		blocks = len / ctx->u.aes.block_size;
  		for (i = 0; i < blocks; i++) {
  			for (j = 0; j < ctx->u.aes.block_size; j++)
  				ctx->u.aes.cbc[j] ^= plain[j];
  			aes_encrypt(ctx->u.aes.ctx_enc, ctx->u.aes.cbc,
  				    ctx->u.aes.cbc);
  			os_memcpy(crypt, ctx->u.aes.cbc,
  				  ctx->u.aes.block_size);
  			plain += ctx->u.aes.block_size;
  			crypt += ctx->u.aes.block_size;
  		}
  		break;
  	case CRYPTO_CIPHER_ALG_3DES:
  		if (len % 8)
  			return -1;
  		blocks = len / 8;
  		for (i = 0; i < blocks; i++) {
  			for (j = 0; j < 8; j++)
  				ctx->u.des3.cbc[j] ^= plain[j];
  			des3_encrypt(ctx->u.des3.cbc, &ctx->u.des3.key,
  				     ctx->u.des3.cbc);
  			os_memcpy(crypt, ctx->u.des3.cbc, 8);
  			plain += 8;
  			crypt += 8;
  		}
  		break;
  	default:
  		return -1;
  	}
  
  	return 0;
  }
  
  
  int crypto_cipher_decrypt(struct crypto_cipher *ctx, const u8 *crypt,
  			  u8 *plain, size_t len)
  {
  	size_t i, j, blocks;
  	u8 tmp[32];
  
  	switch (ctx->alg) {
  	case CRYPTO_CIPHER_ALG_RC4:
  		if (plain != crypt)
  			os_memcpy(plain, crypt, len);
  		rc4_skip(ctx->u.rc4.key, ctx->u.rc4.keylen,
  			 ctx->u.rc4.used_bytes, plain, len);
  		ctx->u.rc4.used_bytes += len;
  		break;
  	case CRYPTO_CIPHER_ALG_AES:
  		if (len % ctx->u.aes.block_size)
  			return -1;
  		blocks = len / ctx->u.aes.block_size;
  		for (i = 0; i < blocks; i++) {
  			os_memcpy(tmp, crypt, ctx->u.aes.block_size);
  			aes_decrypt(ctx->u.aes.ctx_dec, crypt, plain);
  			for (j = 0; j < ctx->u.aes.block_size; j++)
  				plain[j] ^= ctx->u.aes.cbc[j];
  			os_memcpy(ctx->u.aes.cbc, tmp, ctx->u.aes.block_size);
  			plain += ctx->u.aes.block_size;
  			crypt += ctx->u.aes.block_size;
  		}
  		break;
  	case CRYPTO_CIPHER_ALG_3DES:
  		if (len % 8)
  			return -1;
  		blocks = len / 8;
  		for (i = 0; i < blocks; i++) {
  			os_memcpy(tmp, crypt, 8);
  			des3_decrypt(crypt, &ctx->u.des3.key, plain);
  			for (j = 0; j < 8; j++)
  				plain[j] ^= ctx->u.des3.cbc[j];
  			os_memcpy(ctx->u.des3.cbc, tmp, 8);
  			plain += 8;
  			crypt += 8;
  		}
  		break;
  	default:
  		return -1;
  	}
  
  	return 0;
  }
  
  
  void crypto_cipher_deinit(struct crypto_cipher *ctx)
  {
  	switch (ctx->alg) {
  	case CRYPTO_CIPHER_ALG_AES:
  		aes_encrypt_deinit(ctx->u.aes.ctx_enc);
  		aes_decrypt_deinit(ctx->u.aes.ctx_dec);
  		break;
  	case CRYPTO_CIPHER_ALG_3DES:
  		break;
  	default:
  		break;
  	}
  	os_free(ctx);
  }
  
  
  /* Dummy structures; these are just typecast to struct crypto_rsa_key */
  struct crypto_public_key;
  struct crypto_private_key;
  
  
  struct crypto_public_key * crypto_public_key_import(const u8 *key, size_t len)
  {
  	return (struct crypto_public_key *)
  		crypto_rsa_import_public_key(key, len);
  }
  
  
  #ifdef EAP_TLS_FUNCS
  static struct crypto_private_key *
  crypto_pkcs8_key_import(const u8 *buf, size_t len)
  {
  	struct asn1_hdr hdr;
  	const u8 *pos, *end;
  	struct bignum *zero;
  	struct asn1_oid oid;
  	char obuf[80];
  
  	/* PKCS #8, Chapter 6 */
  
  	/* PrivateKeyInfo ::= SEQUENCE */
  	if (asn1_get_next(buf, len, &hdr) < 0 ||
  	    hdr.class != ASN1_CLASS_UNIVERSAL ||
  	    hdr.tag != ASN1_TAG_SEQUENCE) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Does not start with PKCS #8 "
  			   "header (SEQUENCE); assume PKCS #8 not used");
  		return NULL;
  	}
  	pos = hdr.payload;
  	end = pos + hdr.length;
  
  	/* version Version (Version ::= INTEGER) */
  	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
  	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Expected INTEGER - found "
  			   "class %d tag 0x%x; assume PKCS #8 not used",
  			   hdr.class, hdr.tag);
  		return NULL;
  	}
  
  	zero = bignum_init();
  	if (zero == NULL)
  		return NULL;
  
  	if (bignum_set_unsigned_bin(zero, hdr.payload, hdr.length) < 0) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Failed to parse INTEGER");
  		bignum_deinit(zero);
  		return NULL;
  	}
  	pos = hdr.payload + hdr.length;
  
  	if (bignum_cmp_d(zero, 0) != 0) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Expected zero INTEGER in the "
  			   "beginning of private key; not found; assume "
  			   "PKCS #8 not used");
  		bignum_deinit(zero);
  		return NULL;
  	}
  	bignum_deinit(zero);
  
  	/* privateKeyAlgorithm PrivateKeyAlgorithmIdentifier
  	 * (PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier) */
  	if (asn1_get_next(pos, len, &hdr) < 0 ||
  	    hdr.class != ASN1_CLASS_UNIVERSAL ||
  	    hdr.tag != ASN1_TAG_SEQUENCE) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Expected SEQUENCE "
  			   "(AlgorithmIdentifier) - found class %d tag 0x%x; "
  			   "assume PKCS #8 not used",
  			   hdr.class, hdr.tag);
  		return NULL;
  	}
  
  	if (asn1_get_oid(hdr.payload, hdr.length, &oid, &pos)) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Failed to parse OID "
  			   "(algorithm); assume PKCS #8 not used");
  		return NULL;
  	}
  
  	asn1_oid_to_str(&oid, obuf, sizeof(obuf));
  	wpa_printf(MSG_DEBUG, "PKCS #8: algorithm=%s", obuf);
  
  	if (oid.len != 7 ||
  	    oid.oid[0] != 1 /* iso */ ||
  	    oid.oid[1] != 2 /* member-body */ ||
  	    oid.oid[2] != 840 /* us */ ||
  	    oid.oid[3] != 113549 /* rsadsi */ ||
  	    oid.oid[4] != 1 /* pkcs */ ||
  	    oid.oid[5] != 1 /* pkcs-1 */ ||
  	    oid.oid[6] != 1 /* rsaEncryption */) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Unsupported private key "
  			   "algorithm %s", obuf);
  		return NULL;
  	}
  
  	pos = hdr.payload + hdr.length;
  
  	/* privateKey PrivateKey (PrivateKey ::= OCTET STRING) */
  	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
  	    hdr.class != ASN1_CLASS_UNIVERSAL ||
  	    hdr.tag != ASN1_TAG_OCTETSTRING) {
  		wpa_printf(MSG_DEBUG, "PKCS #8: Expected OCTETSTRING "
  			   "(privateKey) - found class %d tag 0x%x",
  			   hdr.class, hdr.tag);
  		return NULL;
  	}
  	wpa_printf(MSG_DEBUG, "PKCS #8: Try to parse RSAPrivateKey");
  
  	return (struct crypto_private_key *)
  		crypto_rsa_import_private_key(hdr.payload, hdr.length);
  }
  #endif /* EAP_TLS_FUNCS */
  
  
  struct crypto_private_key * crypto_private_key_import(const u8 *key,
  						      size_t len)
  {
  	struct crypto_private_key *res;
  
  	/* First, check for possible PKCS #8 encoding */
  	res = crypto_pkcs8_key_import(key, len);
  	if (res)
  		return res;
  
  	/* Not PKCS#8, so try to import PKCS #1 encoded RSA private key */
  	wpa_printf(MSG_DEBUG, "Trying to parse PKCS #1 encoded RSA private "
  		   "key");
  	return (struct crypto_private_key *)
  		crypto_rsa_import_private_key(key, len);
  }
  
  
  struct crypto_public_key * crypto_public_key_from_cert(const u8 *buf,
  						       size_t len)
  {
  	/* No X.509 support in crypto_internal.c */
  	return NULL;
  }
  
  
  static int pkcs1_generate_encryption_block(u8 block_type, size_t modlen,
  					   const u8 *in, size_t inlen,
  					   u8 *out, size_t *outlen)
  {
  	size_t ps_len;
  	u8 *pos;
  
  	/*
  	 * PKCS #1 v1.5, 8.1:
  	 *
  	 * EB = 00 || BT || PS || 00 || D
  	 * BT = 00 or 01 for private-key operation; 02 for public-key operation
  	 * PS = k-3-||D||; at least eight octets
  	 * (BT=0: PS=0x00, BT=1: PS=0xff, BT=2: PS=pseudorandom non-zero)
  	 * k = length of modulus in octets (modlen)
  	 */
  
  	if (modlen < 12 || modlen > *outlen || inlen > modlen - 11) {
  		wpa_printf(MSG_DEBUG, "PKCS #1: %s - Invalid buffer "
  			   "lengths (modlen=%lu outlen=%lu inlen=%lu)",
  			   __func__, (unsigned long) modlen,
  			   (unsigned long) *outlen,
  			   (unsigned long) inlen);
  		return -1;
  	}
  
  	pos = out;
  	*pos++ = 0x00;
  	*pos++ = block_type; /* BT */
  	ps_len = modlen - inlen - 3;
  	switch (block_type) {
  	case 0:
  		os_memset(pos, 0x00, ps_len);
  		pos += ps_len;
  		break;
  	case 1:
  		os_memset(pos, 0xff, ps_len);
  		pos += ps_len;
  		break;
  	case 2:
  		if (os_get_random(pos, ps_len) < 0) {
  			wpa_printf(MSG_DEBUG, "PKCS #1: %s - Failed to get "
  				   "random data for PS", __func__);
  			return -1;
  		}
  		while (ps_len--) {
  			if (*pos == 0x00)
  				*pos = 0x01;
  			pos++;
  		}
  		break;
  	default:
  		wpa_printf(MSG_DEBUG, "PKCS #1: %s - Unsupported block type "
  			   "%d", __func__, block_type);
  		return -1;
  	}
  	*pos++ = 0x00;
  	os_memcpy(pos, in, inlen); /* D */
  
  	return 0;
  }
  
  
  static int crypto_rsa_encrypt_pkcs1(int block_type, struct crypto_rsa_key *key,
  				    int use_private,
  				    const u8 *in, size_t inlen,
  				    u8 *out, size_t *outlen)
  {
  	size_t modlen;
  
  	modlen = crypto_rsa_get_modulus_len(key);
  
  	if (pkcs1_generate_encryption_block(block_type, modlen, in, inlen,
  					    out, outlen) < 0)
  		return -1;
  
  	return crypto_rsa_exptmod(out, modlen, out, outlen, key, use_private);
  }
  
  
  int crypto_public_key_encrypt_pkcs1_v15(struct crypto_public_key *key,
  					const u8 *in, size_t inlen,
  					u8 *out, size_t *outlen)
  {
  	return crypto_rsa_encrypt_pkcs1(2, (struct crypto_rsa_key *) key,
  					0, in, inlen, out, outlen);
  }
  
  
  int crypto_private_key_decrypt_pkcs1_v15(struct crypto_private_key *key,
  					 const u8 *in, size_t inlen,
  					 u8 *out, size_t *outlen)
  {
  	struct crypto_rsa_key *rkey = (struct crypto_rsa_key *) key;
  	int res;
  	u8 *pos, *end;
  
  	res = crypto_rsa_exptmod(in, inlen, out, outlen, rkey, 1);
  	if (res)
  		return res;
  
  	if (*outlen < 2 || out[0] != 0 || out[1] != 2)
  		return -1;
  
  	/* Skip PS (pseudorandom non-zero octets) */
  	pos = out + 2;
  	end = out + *outlen;
  	while (*pos && pos < end)
  		pos++;
  	if (pos == end)
  		return -1;
  	pos++;
  
  	*outlen -= pos - out;
  
  	/* Strip PKCS #1 header */
  	os_memmove(out, pos, *outlen);
  
  	return 0;
  }
  
  
  int crypto_private_key_sign_pkcs1(struct crypto_private_key *key,
  				  const u8 *in, size_t inlen,
  				  u8 *out, size_t *outlen)
  {
  	return crypto_rsa_encrypt_pkcs1(1, (struct crypto_rsa_key *) key,
  					1, in, inlen, out, outlen);
  }
  
  
  void crypto_public_key_free(struct crypto_public_key *key)
  {
  	crypto_rsa_free((struct crypto_rsa_key *) key);
  }
  
  
  void crypto_private_key_free(struct crypto_private_key *key)
  {
  	crypto_rsa_free((struct crypto_rsa_key *) key);
  }
  
  
  int crypto_public_key_decrypt_pkcs1(struct crypto_public_key *key,
  				    const u8 *crypt, size_t crypt_len,
  				    u8 *plain, size_t *plain_len)
  {
  	size_t len;
  	u8 *pos;
  
  	len = *plain_len;
  	if (crypto_rsa_exptmod(crypt, crypt_len, plain, &len,
  			       (struct crypto_rsa_key *) key, 0) < 0)
  		return -1;
  
  	/*
  	 * PKCS #1 v1.5, 8.1:
  	 *
  	 * EB = 00 || BT || PS || 00 || D
  	 * BT = 00 or 01
  	 * PS = k-3-||D|| times (00 if BT=00) or (FF if BT=01)
  	 * k = length of modulus in octets
  	 */
  
  	if (len < 3 + 8 + 16 /* min hash len */ ||
  	    plain[0] != 0x00 || (plain[1] != 0x00 && plain[1] != 0x01)) {
  		wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB "
  			   "structure");
  		return -1;
  	}
  
  	pos = plain + 3;
  	if (plain[1] == 0x00) {
  		/* BT = 00 */
  		if (plain[2] != 0x00) {
  			wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature "
  				   "PS (BT=00)");
  			return -1;
  		}
  		while (pos + 1 < plain + len && *pos == 0x00 && pos[1] == 0x00)
  			pos++;
  	} else {
  		/* BT = 01 */
  		if (plain[2] != 0xff) {
  			wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature "
  				   "PS (BT=01)");
  			return -1;
  		}
  		while (pos < plain + len && *pos == 0xff)
  			pos++;
  	}
  
  	if (pos - plain - 2 < 8) {
  		/* PKCS #1 v1.5, 8.1: At least eight octets long PS */
  		wpa_printf(MSG_INFO, "LibTomCrypt: Too short signature "
  			   "padding");
  		return -1;
  	}
  
  	if (pos + 16 /* min hash len */ >= plain + len || *pos != 0x00) {
  		wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB "
  			   "structure (2)");
  		return -1;
  	}
  	pos++;
  	len -= pos - plain;
  
  	/* Strip PKCS #1 header */
  	os_memmove(plain, pos, len);
  	*plain_len = len;
  
  	return 0;
  }
  
  
  int crypto_global_init(void)
  {
  	return 0;
  }
  
  
  void crypto_global_deinit(void)
  {
  }
  #endif /* CONFIG_TLS_INTERNAL */
  
  
  #if defined(EAP_FAST) || defined(CONFIG_WPS)
  
  int crypto_mod_exp(const u8 *base, size_t base_len,
  		   const u8 *power, size_t power_len,
  		   const u8 *modulus, size_t modulus_len,
  		   u8 *result, size_t *result_len)
  {
  	struct bignum *bn_base, *bn_exp, *bn_modulus, *bn_result;
  	int ret = -1;
  
  	bn_base = bignum_init();
  	bn_exp = bignum_init();
  	bn_modulus = bignum_init();
  	bn_result = bignum_init();
  
  	if (bn_base == NULL || bn_exp == NULL || bn_modulus == NULL ||
  	    bn_result == NULL)
  		goto error;
  
  	if (bignum_set_unsigned_bin(bn_base, base, base_len) < 0 ||
  	    bignum_set_unsigned_bin(bn_exp, power, power_len) < 0 ||
  	    bignum_set_unsigned_bin(bn_modulus, modulus, modulus_len) < 0)
  		goto error;
  
  	if (bignum_exptmod(bn_base, bn_exp, bn_modulus, bn_result) < 0)
  		goto error;
  
  	ret = bignum_get_unsigned_bin(bn_result, result, result_len);
  
  error:
  	bignum_deinit(bn_base);
  	bignum_deinit(bn_exp);
  	bignum_deinit(bn_modulus);
  	bignum_deinit(bn_result);
  	return ret;
  }
  
  #endif /* EAP_FAST || CONFIG_WPS */
  
  
  #endif /* CONFIG_CRYPTO_INTERNAL */
  