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CFB mode in Crypto API in Windows Mobile 5

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I am using Windows Mobile 5 and AES 128 bit block cipher with 128 bit key. When I encrypt a data of 5 bytes, by default of CBC mode, it returns a block length of 16 bytes. After I changed to CFB mode by CryptSetKeyParam(), the 5 byte data still returns 16 bytes when I expected to be 5 bytes.

DWORD dwMode = CRYPT_MODE_CFB;
DWORD dwDataLength;

CryptSetKeyParam(hKey, KP_MODE, (BYTE *)&dwMode, 0);

CryptEncrypt (hKey, 0, bEOF, 0, buffer, &dwDataLength, BLOCK_SIZE)) ;
// buffer is a 5 bytes data
// dwDataLength = 5
// BLOCK_SIZE = 16

what's wrong with my code ?
1) is CFB supported in Windows CE 5.0 ? if yes, what parameters did I miss ?
2) when I check the number of feedback bits in CFB mode by CryptSetKeyParam with KP_MODE_BITS, it returns 0 bit. I supposed this should be 8 bits, correct ?
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