af97ffffa5
* Remove some unused cryptographic code * Add some notes about how Minecraft's cryptography choices have not quite survived the test of time
71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
#include <jni.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <openssl/evp.h>
|
|
#include "jni_util.h"
|
|
|
|
typedef unsigned char byte;
|
|
|
|
JNIEXPORT jlong JNICALL
|
|
Java_com_velocitypowered_natives_encryption_OpenSslCipherImpl_init(JNIEnv *env,
|
|
jclass clazz,
|
|
jbyteArray key,
|
|
jboolean encrypt)
|
|
{
|
|
jsize keyLen = (*env)->GetArrayLength(env, key);
|
|
if (keyLen != 16) {
|
|
throwException(env, "java/lang/IllegalArgumentException", "cipher not 16 bytes");
|
|
return 0;
|
|
}
|
|
|
|
EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
|
|
if (ctx == NULL) {
|
|
throwException(env, "java/lang/OutOfMemoryError", "allocate cipher");
|
|
return 0;
|
|
}
|
|
|
|
// Since we know the array size is always bounded, we can just use Get<Primitive>ArrayRegion
|
|
// and save ourselves some error-checking headaches.
|
|
jbyte keyBytes[16];
|
|
(*env)->GetByteArrayRegion(env, key, 0, keyLen, (jbyte*) keyBytes);
|
|
if ((*env)->ExceptionCheck(env)) {
|
|
return 0;
|
|
}
|
|
|
|
// But, you're saying, *why* are we using the key as the IV? After all, reusing the key as
|
|
// the IV defeats the entire point - we might as well just initialize it to all zeroes.
|
|
//
|
|
// You can blame Mojang. For the record, we also don't consider the Minecraft protocol
|
|
// encryption scheme to be secure, and it has reached the point where any serious cryptographic
|
|
// protocol needs a refresh. There are multiple obvious weaknesses, and this is far from the
|
|
// most serious.
|
|
//
|
|
// If you are using Minecraft in a security-sensitive application, *I don't know what to say.*
|
|
int result = EVP_CipherInit(ctx, EVP_aes_128_cfb8(), (byte*) keyBytes, (byte*) keyBytes,
|
|
encrypt);
|
|
if (result != 1) {
|
|
EVP_CIPHER_CTX_free(ctx);
|
|
throwException(env, "java/security/GeneralSecurityException", "openssl initialize cipher");
|
|
return 0;
|
|
}
|
|
return (jlong) ctx;
|
|
}
|
|
|
|
JNIEXPORT void JNICALL
|
|
Java_com_velocitypowered_natives_encryption_OpenSslCipherImpl_free(JNIEnv *env,
|
|
jclass clazz,
|
|
jlong ptr)
|
|
{
|
|
EVP_CIPHER_CTX_free((EVP_CIPHER_CTX *) ptr);
|
|
}
|
|
|
|
JNIEXPORT void JNICALL
|
|
Java_com_velocitypowered_natives_encryption_OpenSslCipherImpl_process(JNIEnv *env,
|
|
jclass clazz,
|
|
jlong ptr,
|
|
jlong source,
|
|
jint len,
|
|
jlong dest)
|
|
{
|
|
EVP_CipherUpdate((EVP_CIPHER_CTX*) ptr, (byte*) dest, &len, (byte*) source, len);
|
|
} |