Merge branch 'main' into PostMintResponse_and_mypy

docs/specs/04.md

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+# NUT-4 - Mint tokens
+
+After requesting a mint (see #3 [TODO: Link]) and paying the invoice that was returned by the mint, a wallet proceeds with requesting tokens from the mint in return for paying the invoice. 
+
+For that, a wallet sends a `POST /mint&payment_hash=<hash>` request with a JSON body to the mint. The body **MUST** include `BlindedMessages` that are worth a maximum of `<amount_sat>` [TODO: Refer to BlindedMessages]. If successful (i.e. the invoice has been previously paid and the `BlindedMessages` are valid), the mint responds with `Promises` [TODO: Link Promises].
+
+## Example
+
+Request of `Alice`:
+
+```http
+POST https://mint.host:3338/mint&payment_hash=67d1d9ea6ada225c115418671b64a
+```
+
+With the data being of the form `BlindedMessages`:
+
+```json
+{
+	"blinded_messages": 
+		[
+			BlindedMessage,
+			...
+		]
+}
+```
+
+
+With curl:
+
+```bash
+curl -X POST https://mint.host:3338/mint&payment_hash=67d1d9ea6ada225c115418671b64a -d \
+{
+	"blinded_messages": 
+	[
+		{
+		"amount": 2, 
+		"B_": "02634a2c2b34bec9e8a4aba4361f6bf202d7fa2365379b0840afe249a7a9d71239"
+		},
+		{
+		"amount": 8, 
+		"B_": "03b54ab451b15005f2c64d38fc512fca695914c8fd5094ee044e5724ad41fda247"
+		
+		}
+	]
+}
+```
+
+Response of `Bob`: 
+
+If the invoice was successfully paid, `Bob` responds with a `PostMintResponse` which is essentially a list of `BlindedSignature`'s [TODO: Link PostMintResponse]
+
+```json
+{
+"promises":
+	[
+		{
+		"id": "DSAl9nvvyfva",
+		"amount": 2,
+		"C_": "03e61daa438fc7bcc53f6920ec6c8c357c24094fb04c1fc60e2606df4910b21ffb"
+		},
+		{
+		"id": "DSAl9nvvyfva",
+		"amount": 8,
+		"C_": "03fd4ce5a16b65576145949e6f99f445f8249fee17c606b688b504a849cdc452de"
+		},
+	]
+}
+
+```
+
+If the invoice was not paid yet, `Bob` responds with an error. In that case, `Alice` **CAN** repeat the same response until the Lightning invoice is settled.
+
+## Unblinding signatures
+
+Upon receiving the `PostMintResponse` with the list of `BlindedSignature`'s from the mint `Bob`, a wallet `Alice` **MUST** then unblind the `BlindedSignature`'s from `Bob` (see #0 Notation [TODO: Link to unblinding]) to generate a list of `Proof`'s. A `Proof` is effectively an ecash `Token` and can later be used to redeem the token. The wallet **MUST** store the `Proof` in its database.
+
+A list multiple `Proof`'s is called `Proofs` and has the form:
+
+```json
+{
+"proofs" : 
+	[
+		{
+		"id": "DSAl9nvvyfva",
+		"amount": 2,
+		"secret": "S+tDfc1Lfsrb06zaRdVTed6Izg",
+		"C": "0242b0fb43804d8ba9a64ceef249ad7a60f42c15fe6d4907238b05e857527832a3"
+		},
+		{
+		...
+		}
+	]
+}
+```