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112 lines
2.5 KiB
Markdown
112 lines
2.5 KiB
Markdown
---
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id: 68e39ed6106dac2f0a98fd65
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title: "Challenge 83: Signature Validation"
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challengeType: 29
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dashedName: challenge-83
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---
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# --description--
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Given a message string, a secret key string, and a signature number, determine if the signature is valid using this encoding method:
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- Letters in the message and secret key have these values:
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- `a` to `z` have values `1` to `26` respectively.
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- `A` to `Z` have values `27` to `52` respectively.
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- All other characters have no value.
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- Compute the signature by taking the sum of the message plus the sum of the secret key.
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For example, given the message `"foo"` and the secret key `"bar"`, the signature would be `57`:
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```md
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f (6) + o (15) + o (15) = 36
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b (2) + a (1) + r (18) = 21
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36 + 21 = 57
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```
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Check if the computed signature matches the provided signature.
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# --hints--
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`verify("foo", "bar", 57)` should return `True`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("foo", "bar", 57), True)`)
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}})
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```
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`verify("foo", "bar", 54)` should return `False`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("foo", "bar", 54), False)`)
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}})
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```
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`verify("freeCodeCamp", "Rocks", 238)` should return `True`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("freeCodeCamp", "Rocks", 238), True)`)
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}})
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```
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`verify("Is this valid?", "No", 210)` should return `False`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("Is this valid?", "No", 210), False)`)
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}})
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```
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`verify("Is this valid?", "Yes", 233)` should return `True`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("Is this valid?", "Yes", 233), True)`)
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}})
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```
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`verify("Check out the freeCodeCamp podcast,", "in the mobile app", 514)` should return `True`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertIs(verify("Check out the freeCodeCamp podcast,", "in the mobile app", 514), True)`)
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}})
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```
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# --seed--
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## --seed-contents--
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```py
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def verify(message, key, signature):
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return message
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```
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# --solutions--
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```py
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def verify(message, key, signature):
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def charValue(ch) -> int:
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if 'a' <= ch <= 'z':
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return ord(ch) - ord('a') + 1
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elif 'A' <= ch <= 'Z':
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return ord(ch) - ord('A') + 27
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else:
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return 0
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def compute_sum(s):
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return sum(charValue(ch) for ch in s)
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total = compute_sum(message) + compute_sum(key)
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return total == signature
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```
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