Indistinguishable from random (IND)
Indistinguishable from random or IND is often referenced in cryptography text.
See inside for a practical description!
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Indistinguishable from random (IND)
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2 min read
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| A cryptographically-suitable key is a sequence of bits that are |
| indistinguishable from random. In academic literature, it is typically |
| contracted to IND. Others may say that it is "uniformly random" as it was |
| selected from a uniform distribution of possible configurations. |
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| If there is a bias in which states are selected, then it is not uniformly |
| random. Likewise, if there is a bias when it is encoded to binary, then it |
| is not uniformly random in binary. |
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| In practical terms an IND bit string cannot be meaningfully analyzed. It is |
| also impractical to guess or brute force when it is sufficiently long. |
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| You may see names like AES-128 or SHA-256 and wonder what that's about. The |
| names refer to how many bits there are in their configuration or design. |
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| Asymmetric keys and asymmetric computations have distinctive patterns, which |
| makes them unsuitable for use in symmetric cryptography like AES-256. See |
| Why some cryptographic keys are much smaller than others [L1] (archived [L2] |
| ) by CloudFlare. A distinctive pattern makes it not IND! |
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Indistinguishable from random (IND):
It is computationally impractical to determine if an indistinguishable from
random string was truly random or generated through a computational process.
[L1]: https://blog.cloudflare.com/why-are-some-keys-small/
[L2]: https://archive.vn/jhjMm