diff --git a/src/auth/auth.service.ts b/src/auth/auth.service.ts
new file mode 100644
index 0000000..c39ee44
--- /dev/null
+++ b/src/auth/auth.service.ts
@@ -0,0 +1,110 @@
+import { ForbiddenException, Injectable } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+import { AuthLoginDto, AuthRegisterDto } from './dto';
+import * as argon from 'argon2';
+import { Prisma, User } from '@prisma/client';
+import { JwtService } from '@nestjs/jwt';
+import { ConfigService } from '@nestjs/config';
+
+@Injectable()
+export class AuthService {
+  private readonly initialBalance = 1000;
+
+  constructor(
+    private prisma: PrismaService,
+    private jwt: JwtService,
+    private config: ConfigService,
+  ) {}
+
+  async signup(dto: AuthRegisterDto) {
+    const hash = await argon.hash(dto.password);
+    const promoCode = await this.getPromoCode(dto.promoCode);
+    const userRole = await this.getUserRole('user');
+    const balance = this.calculateBalance(promoCode);
+
+    try {
+      const user = await this.createUser(dto, hash, userRole.id, balance);
+      return this.signToken(user);
+    } catch (error) {
+      this.handleSignupError(error);
+    }
+  }
+
+  private async getPromoCode(promoCode: string) {
+    return this.prisma.promoCode.findFirst({
+      where: {name: promoCode},
+    });
+  }
+
+  private async getUserRole(roleName: string) {
+    return this.prisma.role.findFirst({
+      where: {name: roleName},
+    });
+  }
+
+  private calculateBalance(promoCode: any) {
+    let balance = this.initialBalance;
+    if (promoCode && promoCode.value) {
+      balance += promoCode.value;
+    }
+    return balance;
+  }
+
+  private async createUser(dto: AuthRegisterDto, hash: string, roleId: string, balance: number) {
+    return this.prisma.user.create({
+      data: {
+        firstName: dto.firstName,
+        lastName: dto.lastName,
+        pseudo: dto.pseudo,
+        city: dto.city,
+        email: dto.email,
+        hash,
+        age: dto.age,
+        roleId,
+        isActive: true,
+        dollarAvailables: balance,
+      },
+    });
+  }
+
+  private handleSignupError(error: any) {
+    if (error instanceof Prisma.PrismaClientKnownRequestError) {
+      if (error.code === 'P2002') {
+        throw new ForbiddenException('Credentials taken');
+      }
+    }
+    throw error;
+  }
+
+  async signin(dto: AuthLoginDto) {
+    const userDatas = await this.prisma.user.findUnique({
+      where: { email: dto.email },
+      include: {
+        UserHasCrypto: { include: { Crypto: true } },
+        Role: true,
+      },
+    });
+
+    if (!userDatas) throw new ForbiddenException('Credentials incorrect');
+
+    const pwMatches = await argon.verify(userDatas.hash, dto.password);
+    if (!pwMatches) throw new ForbiddenException('Credentials incorrect');
+
+    return this.signToken(userDatas);
+  }
+
+  async signToken(user: any): Promise<{ access_token: string; user: User }> {
+    const payload = { sub: user.id, email: user.email };
+    user.hash = null;
+    const secret = this.config.get('JWT_SECRET');
+    const token = await this.jwt.signAsync(payload, {
+      expiresIn: '30d',
+      secret: secret,
+    });
+
+    return {
+      access_token: token,
+      user,
+    };
+  }
+}
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