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1

To simulate $n$ times iterated ECB encryption, you can set your input plaintext block as the IV, encrypt a "plaintext" consisting of $n$ all-zero blocks using either CBC or CFB mode (which are identical for all-zero plaintext), and take the $n$-th block of the resulting ciphertext (discarding the rest of the output). Note that, if your CBC mode ...

2

First lets acknowledge this is a horrible hack - you really should find a way to do what you want more directly or risk code maintenance issues and likely bugs in the future. Second, while the question isn't about your key strengthening step it seems like you should ask about the security. There are lots of good key derivation methods out there and I don't ...

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I've implemented AES-128 with byte calculations for a small embedded systems, with optional on-the-fly key schedule calculation. See aes-min on github. The key schedule starting point for decryption must be obtained by calculating all the rounds of the key schedule. For a particular key, that decryption key schedule starting point only needs to be done once ...

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If $(R_1,c_1)=(g^{r_1}, A^{r_1}m_1)$ and $(R_2,c_2)=(g^{r_2},A^{r_2}m_2)$ are ciphertexts (with respect to the same public key $A$) corresponding to two messages $m_1$ and $m_2$, then $$(R_1R_2,c_1c_2)=(g^{r_1+r_2},A^{r_1+r_2}m_1m_2)$$ is an encryption of the message $m_1m_2$ (note that the calculations are performed in $\mathbb Z/p\mathbb Z$, that is, ...

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