mirror of
https://gitlab.kit.edu/kit/scc/sys/mail/exim-encrypt-dlfunc.git
synced 2025-12-06 08:33:56 +01:00
First working version of sodium_crypto_secretbox_encrypt_password() and
sodium_crypto_secretbox_decrypt_password().
This commit is contained in:
Heiko Reese
@ -3,67 +3,131 @@
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#include <strings.h>
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#include <sodium.h>
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/* Local encryption key */
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#include "recipient_pk.h"
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/* Exim4 dlfunc API header */
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#include <local_scan.h>
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/*
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* Encrypt the second argument with password from the first argument
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* Encrypt the second argument with password string from the first argument
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* using crypto_secretbox_easy().
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*/
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int sodium_crypto_secretbox(uschar ** yield, int argc, uschar * argv[])
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{
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if (sodium_init() == -1) {
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*yield = string_copy(US "Unable to initialize libsodium");
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return ERROR;
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}
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if (argc != 2) {
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*yield =
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string_sprintf
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("Wrong number of arguments (got %i, expected 2)", argc);
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return ERROR;
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}
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// get password
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unsigned char *password = argv[0];
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size_t passwordlen = strlen((const char *)password);
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int sodium_crypto_secretbox_encrypt_password(uschar **yield, int argc, uschar *argv[]) {
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// ensure libsodium is initialized
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if (sodium_init() == -1) {
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*yield = string_copy(US
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"Unable to initialize libsodium");
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return ERROR;
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}
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// check argument count
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if (argc != 2) {
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*yield = string_sprintf("Wrong number of arguments (got %i, expected 2)", argc);
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return ERROR;
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}
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// get password argument
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unsigned char *password = argv[0];
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size_t passwordlen = strlen((const char *) password);
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// get cleartext message
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unsigned char *message = argv[1];
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size_t messagelen = strlen((const char *)message);
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// get cleartext message argument
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unsigned char *message = argv[1];
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size_t messagelen = strlen((const char *) message);
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/*
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* Derive a key from the password.
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* This operations needs to be fast (exim holds no state, this might be called once or mutliple times per email).
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* Collisions avoidance or brute force arracks are not a concern here.
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*/
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unsigned char keybytes[crypto_secretbox_KEYBYTES];
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sodium_memzero(keybytes, crypto_secretbox_KEYBYTES);
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crypto_generichash(keybytes, crypto_secretbox_KEYBYTES,
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password, passwordlen, NULL, 0);
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/*
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* Derive a key from the password using a generic hash.
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* This operations needs to be fast (exim holds no state, this might be called once or multiple times per email).
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* Collisions avoidance or brute force attacks are not a concern here.
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*/
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unsigned char keybytes[crypto_secretbox_KEYBYTES];
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sodium_memzero(keybytes, crypto_secretbox_KEYBYTES);
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crypto_generichash(keybytes, crypto_secretbox_KEYBYTES,
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password, passwordlen, NULL, 0);
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// prepare buffer for ciphertext
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unsigned int cipherlen = messagelen + crypto_secretbox_MACBYTES;
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unsigned char *ciphertext = malloc(cipherlen);
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sodium_memzero(ciphertext, cipherlen);
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// prepare buffer for ciphertext
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unsigned int cipherlen = messagelen + crypto_secretbox_MACBYTES;
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unsigned char *ciphertext = (unsigned char *) store_get(cipherlen);
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sodium_memzero(ciphertext, cipherlen);
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// encrypt message
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unsigned char nonce[crypto_secretbox_NONCEBYTES];
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randombytes_buf(nonce, sizeof nonce);
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crypto_secretbox_easy(ciphertext, message, messagelen, nonce, keybytes);
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// encrypt message
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unsigned char nonce[crypto_secretbox_NONCEBYTES];
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randombytes_buf(nonce, sizeof nonce);
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crypto_secretbox_easy(ciphertext, message, messagelen, nonce, keybytes);
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// base64-encode the ciphertext
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unsigned int outputsize = sodium_base64_ENCODED_LEN(cipherlen,
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sodium_base64_VARIANT_ORIGINAL);
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unsigned char *outstring = malloc(outputsize);
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sodium_memzero(outstring, outputsize);
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sodium_bin2base64((char *const)outstring, outputsize,
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ciphertext, cipherlen,
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sodium_base64_VARIANT_ORIGINAL);
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free(ciphertext);
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// combine nonce and ciphertext
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size_t combined_message_len = crypto_secretbox_NONCEBYTES + cipherlen;
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unsigned char * combined_message = store_get(combined_message_len);
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memcpy(combined_message, nonce, crypto_secretbox_NONCEBYTES);
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memcpy(&combined_message[crypto_secretbox_NONCEBYTES], ciphertext, cipherlen);
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// return base64-encoded ciphertext
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*yield = string_copy(outstring);
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free(outstring);
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return OK;
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// base64-encode the ciphertext
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unsigned int outputsize = sodium_base64_ENCODED_LEN(combined_message_len,
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sodium_base64_VARIANT_ORIGINAL);
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unsigned char *outstring = (unsigned char *) store_get(outputsize);
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sodium_memzero(outstring, outputsize);
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sodium_bin2base64((char *const) outstring, outputsize,
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combined_message, combined_message_len,
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sodium_base64_VARIANT_ORIGINAL);
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// return base64-encoded ciphertext
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*yield = string_copy(outstring);
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return OK;
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}
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/*
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* Decrypt the second argument with password string from the first argument
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* using crypto_secretbox_open_easy().
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*/
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int sodium_crypto_secretbox_decrypt_password(uschar ** yield, int argc, uschar * argv[])
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{
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// ensure libsodium is initialized
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if (sodium_init() == -1) {
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*yield = string_copy(US "Unable to initialize libsodium");
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return ERROR;
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}
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// check argument count
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if (argc != 2) {
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*yield =
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string_sprintf
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("Wrong number of arguments (got %i, expected 2)", argc);
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return ERROR;
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}
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// get password
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unsigned char *password = argv[0];
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size_t passwordlen = strlen((const char *)password);
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// Derive key from the password.
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unsigned char keybytes[crypto_secretbox_KEYBYTES];
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sodium_memzero(keybytes, crypto_secretbox_KEYBYTES);
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crypto_generichash(keybytes, crypto_secretbox_KEYBYTES,
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password, passwordlen, NULL, 0);
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// get base64 encoded ciphertext message
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unsigned char *ciphertextb64 = argv[1];
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size_t ciphertextb64len = strlen((const char *) ciphertextb64);
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// base64-decode the ciphertext
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unsigned int combined_message_len = ciphertextb64len / 4 * 3;
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unsigned char *combined_message = (unsigned char *) store_get(combined_message_len);
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sodium_memzero(combined_message, combined_message_len);
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sodium_base642bin(combined_message, combined_message_len,
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(const char *) ciphertextb64, ciphertextb64len,
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NULL, NULL, NULL,
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sodium_base64_VARIANT_ORIGINAL);
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// extract nonce
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unsigned char nonce[crypto_secretbox_NONCEBYTES];
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memcpy(nonce, combined_message, crypto_secretbox_NONCEBYTES);
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// prepare buffer for cleartext
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unsigned int cleartextlen = combined_message_len - crypto_secretbox_NONCEBYTES - crypto_secretbox_MACBYTES;
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unsigned char *cleartext = (unsigned char *) store_get(cleartextlen+1);
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sodium_memzero(cleartext, cleartextlen+1);
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// decrypt message
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if (crypto_secretbox_open_easy(cleartext, &combined_message[crypto_secretbox_NONCEBYTES],
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combined_message_len - crypto_secretbox_NONCEBYTES, nonce, keybytes) != 0) {
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*yield = string_copy((unsigned char *) "Unable to decrypt.");
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return ERROR;
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}
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// return base64-encoded ciphertext
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*yield = string_copy(cleartext);
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return OK;
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}
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@ -3,34 +3,36 @@
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#include <strings.h>
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#include <sodium.h>
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/* Local encryption key */
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#include "recipient_pk.h"
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/* Exim4 dlfunc API header */
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#include <local_scan.h>
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/*
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* Encrypt first argument with fixed public key from recipient_pk.h
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* Encrypt the second argument with the public key from the first argument
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*/
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int sodium_crypto_box_seal_kit(uschar ** yield, int argc, uschar * argv[])
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/*
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int sodium_crypto_box_seal(uschar ** yield, int argc, uschar * argv[])
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{
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size_t messagelen;
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unsigned char *message;
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unsigned char *message, *key;
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if (sodium_init() == -1) {
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*yield = string_copy(US "Unable to initialize libsodium");
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return ERROR;
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}
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if (argc != 1) {
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if (argc != 2) {
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*yield =
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string_sprintf
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("Wrong number of arguments (got %i, expected 1)", argc);
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("Wrong number of arguments (got %i, expected 2)", argc);
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return ERROR;
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}
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// get cleartext message
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message = argv[0];
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messagelen = strlen((const char *)message);
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// get key
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key = argv[1];
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// prepare buffer for ciphertext
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unsigned int cipherlen = messagelen + crypto_box_SEALBYTES;
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unsigned char *ciphertext = malloc(cipherlen);
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@ -56,3 +58,4 @@ int sodium_crypto_box_seal_kit(uschar ** yield, int argc, uschar * argv[])
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return OK;
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}
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*/
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