# How do I …?

This page addresses a bunch of questions of the form “how do I do xyz in Cryptimeleon?”. Consider it Stack-Overflow-style help.

# How do I do group operations and pairings?

# How do I hash into \(\mathbb{Z}_n\)?

You can use `HashIntoZn`

for this.

```
BigInteger n = BigInteger.valueOf(99991); //just for the sake of example
HashIntoZn hashFunction = new HashIntoZn(n);
Zn.ZnElement hashVal = hashFunction.hash("Preimage");
```

# How do I hash into a group \(\mathbb{G}\)?

Bilinear groups provide hash functions as follows:

```
GroupElement hashValue = bilinearGroup.getHashIntoG1().hash("Preimage");
```

For other groups, there may be classes like named like `HashIntoSecp256k1`

.