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    <p>Your code is based upon the <strong>SecKeyWrapper</strong> class from Apple's <a href="http://developer.apple.com/library/ios/#samplecode/CryptoExercise/Introduction/Intro.html" rel="nofollow"><strong>'CryptoExercise' example</strong></a>. I just ran into the same error message when using the doCipher method.</p> <p>'<strong>-4301</strong>' is in this case the value of the ccStatus variable after the call of <strong>CCCryptoFinal</strong>, which returns a value of type <strong>CCryptorStatus</strong>. It is defined in CommonCryptor.h as follows:</p> <pre><code>enum { kCCSuccess = 0, kCCParamError = -4300, kCCBufferTooSmall = -4301, kCCMemoryFailure = -4302, kCCAlignmentError = -4303, kCCDecodeError = -4304, kCCUnimplemented = -4305 }; </code></pre> <p>So somehow the buffer created in the doCipher method is too small, which is odd, because it's size is determined via <strong>CCCryptorGetOutputLength</strong>, just as the documentation of <strong>CCCryptorFinal</strong> suggests:</p> <pre><code>@result kCCBufferTooSmall indicates insufficent space in the dataOut buffer. The caller can use CCCryptorGetOutputLength() to determine the required output buffer size in this case. The operation can be retried; no state is lost when this is returned. </code></pre> <p>I've got the hunch that the SecKeyWrapper class from the Apple <strong>example</strong> is not bug free. I'll see if I can solve the problem or find another way to do AES encryption on iPhone. There's an explanation and example code in Rob Napier's and Mugunth Kumar's book <a href="http://iosptl.com/" rel="nofollow"><strong>'iOS 5 programming - Pushing the limits'</strong></a> that I'll try out. Also, the authors recommend two WWDC Sessions, available at <a href="http://developer.apple.com" rel="nofollow">developer.apple.com</a>.</p> <ul> <li>WWDC 2010, "Session 204: Creating Secure Applications"</li> <li>WWDC 2011, "Session 208: Securing iOS Applications"</li> </ul> <p><strong>EDIT:</strong></p> <p>I just found the error. It's within the <strong>doCipher</strong> method. Simply substitute the following lines:</p> <pre><code>// We don't want to toss padding on if we don't need to if(encryptOrDecrypt == kCCEncrypt) { if(*pkcs7 != kCCOptionECBMode) { if((plainTextBufferSize % kCCBlockSizeAES128) == 0) { *pkcs7 = 0x0000; } else { *pkcs7 = kCCOptionPKCS7Padding; } } } else if(encryptOrDecrypt != kCCDecrypt) { LOGGING_FACILITY1( 0, @"Invalid CCOperation parameter [%d] for cipher context.", *pkcs7 ); } </code></pre> <p>with the following lines:</p> <pre><code>// check for valid context parameter if (encryptOrDecrypt != kCCEncrypt &amp;&amp; encryptOrDecrypt != kCCDecrypt) { LOGGING_FACILITY1( 0, @"Invalid CCOperation parameter [%d] for cipher context.", encryptOrDecrypt ); } </code></pre> <p>As Ortwin pointed out below, you furthermore have to replace the third parameter in the subsequent CCCryptorCreate call to be always kCCOptionPKCS7Padding:</p> <pre><code>// Create and Initialize the crypto reference. ccStatus = CCCryptorCreate( encryptOrDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding, (const void *)[theSymmetricKey bytes], kCCKeySizeAES128, (const void *)iv, &amp;thisEncipher ); </code></pre>
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    1. POiPhone: Decryption error "***** with encipherment ccStatus == -4301"
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    1. COSo basically you remove the complete first if case, because it will lead to the error. Due to the removal of the first if-case, the else-if-case turns into a simple if-case, so the condition needs to hold also the previous else part, i.e. encryptOrDecrypt != kCCEncrypt.
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    2. COyour solution doesn't work for me. When encrypting a 34 byte long string and decrypting it again, the result is only 32 bytes long, the last 2 chars are cut off.
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      1. USOrtwin Gentz
 

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