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keysize

Returns the keysize, which is 32 (bytes). The Rijndael cipher actually supports keylengths of 16, 24 or 32 bytes, but there is no way to communicate this to Crypt::CBC.

Crypt-CBC

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When the last block of plaintext is shorter than the block size, it must be padded. Padding methods include: "standard" (i.e., PKCS#5), "oneandzeroes", "space", and "null".