AES CBC mode problem

[Bian]

Hi,

I test AES CBC mode with below test case(from RFC 3602 section 4). I meet some 
questions which are strange for me.
(I use openssl-0.9.8g, under WidowsXP, VC6++),
 
1 EVP_EncryptFinal_ex() shall be called after calling EVP_EncryptUpdate(), or 
not if the block  is just 16 bytes long
2 when I decrypt the ciphertest from the test case , why failed

from RFC 3602 section 4: 
Case #1: Encrypting 16 bytes (1 block) using AES-CBC with 128-bit key
Key       : 0x06a9214036b8a15b512e03d534120006
IV        : 0x3dafba429d9eb430b422da802c9fac41
Plaintext : "Single block msg"
Ciphertext: 0xe353779c1079aeb82708942dbe77181a

below is my test progarm

unsigned char *EncryptTest(unsigned char *in, int inl, unsigned char *key, 
unsigned char *iv, int *outl)
{
    EVP_CIPHER_CTX ctx;
    int ret;
    EVP_CIPHER_CTX_init(&ctx);
    ret = EVP_CIPHER_CTX_set_padding(&ctx, 0); //0 for no padding, 1 for padding
    if(!ret) abort();
    ret = EVP_EncryptInit_ex(&ctx, EVP_aes_128_cbc(), 0, key, iv);
    if(!ret) abort();
    cout<<"EVP_CIPHER_CTX_block_size: "<<EVP_CIPHER_CTX_block_size(&ctx)<<endl; 
 // 16
    cout<<"EVP_CIPHER_CTX_key_length: "<<EVP_CIPHER_CTX_key_length(&ctx)<<endl; 
 // 16
    cout<<"EVP_CIPHER_CTX_iv_length: "<<EVP_CIPHER_CTX_iv_length(&ctx)<<endl;  
// 16
    unsigned char *out=0;
    *outl=0;
    out = (unsigned char *)malloc(inl + EVP_CIPHER_CTX_block_size(&ctx));
    int len=0;
    
    ret = EVP_EncryptUpdate(&ctx, out, outl, in, inl); 
    if(!ret) abort();
    len += *outl;

    //  code here will lead to return 32 bytes long
   //  without below code, the result is right, I get right ciphertext as test 
case. Why????????????????????????
    /*  
    ret = EVP_EncryptFinal_ex(&ctx, out+len, outl);
    if(!ret) abort();
    len += *outl;
    *outl = len;
    */
    
    return out;
}

The decrypt program:

unsigned char *DecryptTest(unsigned char *in, int inl, unsigned char *key, 
unsigned char *iv, int * outl)
{
    int ret;
    EVP_CIPHER_CTX ctx;
    EVP_CIPHER_CTX_init(&ctx);
    
    ret = EVP_DecryptInit_ex(&ctx, EVP_aes_128_cbc(), 0, key, iv);
    if(!ret) abort();
    cout<<"EVP_CIPHER_CTX_block_size: "<<EVP_CIPHER_CTX_block_size(&ctx)<<endl; 
// 16
    cout<<"EVP_CIPHER_CTX_key_length: "<<EVP_CIPHER_CTX_key_length(&ctx)<<endl; 
 // 16
    cout<<"EVP_CIPHER_CTX_iv_length: "<<EVP_CIPHER_CTX_iv_length(&ctx)<<endl;  
// 16  here
    
    
    unsigned char *out=0;
    *outl=0;
    out = (unsigned char *)malloc(inl + EVP_CIPHER_CTX_block_size(&ctx)+1);
    int len=0;
    ret = EVP_DecryptUpdate(&ctx, out, outl, in, inl );   // inl=16 here, if I 
set inl>16, I can get right result, why ????????????????????
    if(!ret) abort();
    len += *outl;      // *outl = 0 here, why?????????????????????????????????

    ret = EVP_DecryptFinal_ex(&ctx, out, outl);  
    if(!ret) abort();           // !!! abort here, why 
??????????????????????????????????????
    len += *outl;

    ret = EVP_CIPHER_CTX_cleanup(&ctx);
    if(!ret) abort();

    *outl = len;
    
    return out;
}

The main :
    
    int i;
    unsigned char key[]={
        0x06,0xa9,0x21,0x40,
        0x36,0xb8,0xa1,0x5b,
        0x51,0x2e,0x03,0xd5,
        0x34,0x12,0x00,06
    };
    unsigned char iv[]={
        0x3d,0xaf,0xba,0x42,
        0x9d,0x9e,0xb4,0x30,
        0xb4,0x22,0xda,0x80,
        0x2c,0x9f,0xac,0x41
    };
    char Plaintext[]="Single block msg";
    unsigned char Ciphertext[]={
        0xe3,0x53,0x77,0x9c,
        0x10,0x79,0xae,0xb8,
        0x27,0x08,0x94,0x2d,
        0xbe,0x77,0x18,0x1a
    };
    
    unsigned char *out;
    int outl;
    out = EncryptTest((unsigned char*)Plaintext, sizeof(Plaintext), key,iv, 
&outl);
    printf("Ciphertext: ");
    for(i=0; i<outl; i++)
        printf("%.2x",out[i]);
    printf("\n");

    unsigned char *out2;
    int outl2;
    out2 = DecryptTest(Ciphertext, sizeof(Ciphertext), key,iv, &outl2);
    free(out);
    free(out2);


bian


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